Panasonic AG-7700 help needed

[Malcolm G6ANZ]

Confession time! I have a Panasonic AG-7700 VHS. This was working quite well after a major recapping of most of the surface mount electrolytic caps. I was going through a setup trying to improve the picture quality, probably not needed, and it decided not to eject the cassette. The load arms, that wrap the tape round the head drum did not fully retract and it showed an error , basically it said that there was an error in the tape load path. Really helpful. At this point I manually unthreaded the tape from the head drum and guides and carefully removed the cassette. By turning the load motor pulley by hand I could feel when the system 'stalled' Obviously there was something jamming the mechanism. To start eliminating probable causes I first took off the capstan pressure roller and then tried to unload, same fault. After more investigation I removed the drive assembly and found that the quadrant driving the loading arms was very stiff . By slackening off the pivots and applying a little silicone grease the arms moved correctly and the system would load and unload correctly. Fault cured. I now have a mechanism without the pinch roller fitted. Also I have had to remove the cassette carriage. I have followed the manual instructions to replace the pinch roller and although it all seems to go back correctly it jams up.
I have also got a small piece of nylon and I cant figure out where it came from!
The only items I have disturbed are the pinch roller and the cassette holder, one was to identify the place of the fault and the other to extract the tape.
So, does anyone have knowledge of these machines and can point me in the right direction of fixing it.
I did take photos but ,as usual, they don't show the faulty bit.

Malcolm