A special Thank You to Cosmas on youtube for explaining and showing how this works. I have the Harbor Freight label of the same machine. I bought it used and it quit oscillating after just a couple of uses. The model has changed and H.F. no longer sells this one, but with your demo I decided it would be worth a search to buy the correct belt. The narrow belt was worn and had a loose spot where the outer layer was torn and the belt was not broken through. I crossed the number from another model and found that both these drive belts are commonly used in multiple applications. Found one with shipping for under $5 U.S. The sander now works fine again! Thanks. To LJs out there, this is one of those tools found with many different labels and at varying price points. I needed the narrow (0.25”) 16” drive belt and found the part on fleabay. Many different sources had it readily available once I got the complete description 80 teeth (5 per inch) 16” belt 0.25” wide. Very easy fix when one might consider trashing it because it is a HF anchor. It actually works quite well.
-- Like Guy Clark sez - "Sometimes I use my head, Sometimes I get a bigger hammer"