Sigma 18-200 1:3.5-6.3 DC OS HSM repair: how to open up the lens?

I got a Sigma 18-200 1:3.5-6.3 DC OS HSM for my Nikon D3100 but the lens stabilisation has a problem. When zooming in and out the lens shakes to the to left corner. I opened up the lens and fiddled with the flex/flat/ribbon cable the goes into the central lens assembly and this increased the lens shaking. This leads me to believe this ribbon cable is broken. As this cable bends each time when changing zoom this is no surprise.

My problem is that I'm not sure which screws to remove next. It should be perfectly possible to disassemble the lens, but what would be the next step? My guess would be the zoom ring but I can't find a way to take it off, unless the encoder brushes' screws also keep the zoom ring in place.

I made a photo of how far I got:

http://images.bluefan.nl/DSC_0012_sc.JPG

The ribbon cable on the left goes to the green PCB and I suspect the traces are broken so that the magnets get intermittend power which makes the lens shake. To check it with a multimeter I need to get to the green pcb the correct way and not end up with parts fallen into an inaccessible lens.

Any help or suggestions is welcome!