I admire your frugality. But:
01-02-08: David6fl
I found the problem with tracking. The rubber drive belt from the servo was old and slipping. I took it off and cleaned it with isopropyl alcohol. Then I did what I do on my laser printers when the paper pickup starts causing problems. I put a light coating of automotive belt dressing on the pulleys and belt.
If you can scrounge up $12.90, you can get a new belt!