Rewind or fast forward

Try cleaning the pinch roller. A cotton bud dipped in methylated spirits should work, you may need several. Play a tape through to clean off the methanol residue. Avoid touching any semionductors !

If this doesn't work, you've just a tired motor.

Though not familiar with this model, VCRs of all sorts have an idler mechanism which drives the supply and takeup spindles. Either the idler is somehow defective and slipping, and, assuming this idler is belt driven, the belt may be slipping just enough to cause a no Rew/FFW condition. If you had access to a test tape jig (a clear dummy tape, which allows a tech to view what is happening in the area normally obscured by the loaded tape), this might give a clue as to what is happening. On alot of machines, a problem with Rew/FFW would also mean a tape takeup problem in standard play, result in tape spilling out inside the machine. Sensors would catch this condition and go into a error mode, as yours is doing. One other thing which might be happening here, is the pinch roller not being disengaged from the capstan in the Rew/FFW modes. I think this is where I'd look first, and you can probably see if such is happening just by pulling the cover off the VCR. The pinch roller is just to the right of the rotating video head. In the play and forward/rev search modes it will press the tape up against the capstan (a rotating shaft). When in Rew/FFW, the pinch roller should be pulled back from the capstan, maybe 1/4 inch or so. Whatever the case, repair will likely take someone tech savvy. Costs might not be economically justified, with the low-cost, disposable rigs sold in the last 10+ years.