Cannot remove Metz flash from a65!!!

Hey guys.

I have a problem with my flash. Yesterday i had a problem with a defect contact. I had no flash until i push the flash down or move it a little bit. After i moved the camera around (90° pictures) i didnt work again. Today i testet it, for example with small pieces of paper under the flash mount.

Now i cannot remove the flash any more! I can't rotate the big knurled screw in any direction!!! I had this problem 3 times ago, but then i need just a little bit more force, but now i have no chance!

Well - i can move the camera around, no defect contact any more. But i would prefer a removable flash at all:-D

Any solutions?:-(