Hello Filmdude405!
It appears to be the clock work in your camera that may need a cleaning.
You will need a tool to screw off the collar surrounding the shutter release button. A piece of thin leather and a suitable pliers may be sufficient (the leather both to apply the needed friction and to prevent the collar from getting scratched by the jaws of the pliers). Unscrew counterclockwise (cock the shutter first). Take notice of the shims and their order underneath the collar when you lift off the winding lever and the shutter release button.
Inside the shutter release button there is a short rod. Don't loose that, you will need it when using a cable release. I believe there are 3 shims surrounding the shutter release button. One of them with a short "tale". Remember which side of this shim that is facing up, I believe I remember this had importance. (It's been a while since I last "opened" a SRT. I am writing this out of memory.) Lay the winding lever, collar, shutter button and shims aside.
The red lens mount index is hiding a screw. By using a thin pin and gently forcing the pin down between the red index and the tiny collar surrounding it, and flipping the red index up, you will get to the screw. Hold a finger over the red index when flipping it up, to prevent it from flying off. The red index mark is made out of a tiny piece of thin aluminium. it is held in place by an adhesive of some sort.
Lay the red index, the collar and the screw aside.
(By getting off the shutter release button collar and the screw underneath the red index, you are past the "worst" part.)
Turn the shutter speed dial to 'B' and turn the ASA to '6400'. Screw off the tiny screw beside 'ASA' and lift off the shutter time dial. There is a spring underneath the black shutter speed scale plate, hold that plate down with a finger when lifting off the shutter speed dial and remove the finger slowly when setting aside the dial. Don't loose that tiny screw.
Lift up the rewind lever knob to open the camera back. Place a screw driver into the 'fork' at the end of the rewind shaft and turn the rewind lever knob counterclockwise to screw off the rewind lever knob.
There is a tiny shim between the rewind lever knob and the rewind lever shaft. Counterclockwise screw off the flat disc shaped 'nut' underneath the rewind lever knob (this will be easier if the rewind lever shaft is pushed a bit down. Make sure not to push the shaft all the way down so it gets loose inside the camera.)
Now you can screw out the screw on the right side of the camera (exposure counter window side) and the screw on either side of the viewfinder. Place the camera on the table and lift off the camera top. It is a tight fit, so you may have to wiggle the top some to get it off. Once the top is off, take that flat disc shaped 'nut' and screw it back in place around the rewind shaft. The mechanism that is influenced by the input from the shutter speed dial, the ASA selector and the aperture lever (the aperture follower lever around the camera mount) is held in place only by the tension from the cords coming from these inputs. Putting the flat disc shaped 'nut' back in place will prevent the mechanism from falling out, should the camera be held upside down. (It may not fall out even if the camera should be held upside down, it's just to be on the safe side.)
The clockwork mechanism that slows down the release of the second shutter curtain is located near the rear edge, between the shutter speed dial and shutter release button. Put on again both the shutter speed dial and the wind lever and shutter release button.
Soak a Q-tip in isopropanol and then press it lightly against the clock work, making sure the gears get moistened. Turn the shutter speed dial back and forth repeatedly between '1' and 'B' (not too quickly, the clock work needs to keep up...).
Select 'B' and release the shutter. You may have to repeat this cleaning exercise to clean out the clock work. Don't let the isopropanol find its way down into the camera. (Well, at least not too much of it...)
By putting both the film advance lever, the shutter release button and the shutter speed dial back in place, it will be easier to alternate between '1' and 'B' (to work the isopropanol into the clockwork mechanism gears), and to trip the shutter to find out if your effort has succeeded in restoring 'B'.
If there are dust particles between your viewfinder and the prism, now you have the opportunity to clean it out. There is one small screw either side of the eyepiece housing.
Remove those two screws, and lift out the eyepiece housing. Take care of the two cords, one running above the eyepiece housing (running between the shutter speed dial and the mechanism underneath the rewind knob) and one cord underneath the eyepiece running between the shutter speed dial and a spring loaded "take-up spool" left of the eyepiece. Don't touch that spring loaded "take-up spool. It drives the clamp showing the shutter speed in the viewfinder.
If there are dust particles in the viewfinder (dust particles that appear to have "sharp" edges, are located between the prism and the focusing screen. Dust particles that seem to have "soft" edges, are located on the side of the focus screen facing the mirror.) To lift out the prism, the coloured tiny wires running across the top of the prism need to be untwisted/"loosened up".
Unscrew the two screws holding down the square shaped U and lift it off. It is attached to the flash sync wire (you may clean the piece that makes contact with the hotshoe in the camera top) . Lift off the prism and set it down beside the camera front in a way that doesn't put strain on the wires.
Between the prism and focus screen you will find a metal mask that also covers the light meter needle housing to the upper left corner of the finder. Lift off the metal mask. The mask is very thin, so be gentle.
Now you have access to the glass lens above the focus screen. Be VERY gentle when cleaning dust here. The shutter speed scale is glued at each end of the scale. The glue is old and may be brittle. It can be a fiddly task gluing the scale back in place. Take your time! It is very easy to get more dust particles in than you are trying to clean out.
Now you also have access to the light meter needle housing. The light meter needle is moving inside a horizontal rectangular opening the the light meter needle housing.
On either side of this rectangular opening there is a small foam cushion to soften/prevent the light meter needle from "crashing" into the sides of this rectangle.
With age these foam cushions may become sticky, causing the light meter needle to stick in the upper position (when the light meter is turned off for a length of time).
Using a thin needle shaped tool these foam cushions can be removed and the surface they were attached to can be cleaned. You don't have to replace these cushions. (Set the light meter to 'Battey Check' to get the light meter needle out of the way, and set it to 'Off' to get the light meter needle out of the way when working on the opposite side).
You may check the cord running between the mechanism underneath the rewind knob and the aperture follower lever around the camera mount to see if it is running as it should. Move the lever and follow the cord and you will understand how it works.
When you are done cleaning, then you put back the (clean) metal mask, insert the prism and screw it tight and retwist the coloured tiny wires. Screw back the eyepiece housing, remove both the shutter speed dial, the wind lever and the shutter release button, and remove the flat disc shaped nut from the rewind shaft, and then put back on the camera top. If the red index is marked from the needle, a red marker pen may disguise that. A tiny drop of nail polish will act as glue and keep the red index in place inside the tiny collar (and also make it easy to remove again, if needed).
If the ASA showing isn't centered in the "window" (ex. if ASA 200 isn't showing in the "window" as 200 with one white dot on each side of 200, then lift off the shutter speed dial, turn it 180 degrees and put it back on.)
If you also have cleaned all the small pieces before putting the camera back together again, you may very well be pleased with the result of your work.
And, - take your time. Everybody can judge the quality of your work. No one can see how long time you spent.
Regards
