I hadn't thought of tilting as the cause. Yes, it is gravity tension setup. Might even have happened when I first got the saw and, with a friend, had to man handle it out of the back of my cargo van. We might have tilted it on its front side allowing the motor to pivot toward the arbor. That could account for there being no wear polishing on two of the pulley grooves too.
I have a new belt on order from Renovo Parts.
While on the subject, you saw my riving knife thread, I think. Near the end of her video, the YouTube poster had to grind a notch apparently about 1/4" deep in the cast iron motor mount, to allow clearance for the lower end of the RK when the blade is all the way down. The OEM belt is 27", which has the two shafts about a foot apart as the motor hangs from the arbor shaft.
Do you think I could install a 28" belt instead (Renovo has one), so the motor would hang 1/2" lower to allow clearance without grinding the mount?