This may not be the best choice, but it was definitely the cheapest. I just squirted some WD-40 into the setbelt swivel. Used the little red WD-40 pipe to give it just the smallest squirt. Then worked the swivel back and forth a bit and the squeek has been gone for 6 months.

My theory is that the swivel just got some dust or dirt in it and the WD floated it out of the contact area.

 

Ok, it's still making noise. Please someone post a pic of what to oil cause I'm about to sell this thing!