Bobby -
My hunch is that you have a problem with the control magnet (wig wag) and spin cam bar somewhere. Seems like something is allowing the basket to enter spin mode while agitating, and when this shift or partial shift occurs, you hear a squeal from the belt, and you hear this same squeal again when the machine shifts properly at spin time.
The parts that move to allow a proper spin operation are the left-side wig wag plunger, the left cam bar, the yoke support at the tip of the spin cam bar, and the clutch plate within the basket drive. This is a lot of parts to move all at once. The whole shift when done correctly takes no more than a second or two.
Someone else wrote about something related in a current post, and I suggested the same thing - make sure all the moving parts are well lubricated, not bound or able to be bound, that your belt is properly fresh and tightened, and that your wig wag is working correctly. If you are getting a spin condition during agitate, something is wrong - either there is an errant but temporary electrical signal going to the wig wag to energize spin (timer issue) or the wig wag is doing so mechanically. Even then, it sounds like the shift is encountering friction or your belt is really loose.
I have one machine that came in with a failed wig-wag, in which the machine spins full-time and at certain times will agitate at the same time. This is due to a bent plunger on the wig-wag.
Check there first!
Gordon