Hi
I have a GR-DVL140E that trashes the tape when doing backward picture search. It runs OK in normal forward playback. I have had the drive disassebled almost completely and re-assembled to fix a problem with the back tension arm. I can feel that when it runs in backward search mode, it does not break the right tape wheel, so the tape is completely untight. If I press it lightly against the tape guide arm to the right of the pinch roller, it runs OK. And when I remove the pressure, the tape flaps over the top of the arm and crashes because there is no backtension.
There is only one break at the takeup (right) tape wheel, and this is disengaged when it runs backward. It seems it would work it this break was engaged to provide backtension, but I don't know if this meant to be so. It is a quite strong break, normally used to stop the tape after rewinding, I think.