Scrunched Paper on Canon PC-20 Copier

The paper goes askew just before it goes through the heat roller. With the paper tray to the left, top open, you can see a small black pinch wheel (about 5/8" in diam by 3/16" wide) back and to the left, to the right of the heat roller, and just forward of what looks to be some sort of guide ( a flexible plastic strip about 3/16" wide and 3" long with a small spring at one end. I would assume the edge of the paper is supposed to run under the strip and then go under the pinch wheel, but instead it seems to be cocked at a slight angle so it sometimes misses the pinch wheel. It is then crooked before it goes under the heat roller and so gets wrinkled there. This does not happen on each pass, some are O.K. Also the image on the paper is complete, the trouble occurs just before it gets fused by the heat roller. Any ideas as to why the paper shifts slightly and misses the pinch wheel. It appears to me that it wouldn't have to be much out of alignmnent as the wheel is quite narrow and only mates with the far edge of the paper. (There is no pinch wheel for the other paper edge.) Your help is very much appreciated! Frank P.S. Please let me know if the paper path is not what I think it is. Although very old, this has been a great copier and has been amazingly trouble free, so I'm hesitant to dump it!