machine starts spin cycle ok runs up to speed for about 1 minute
then slows down a minute then speeds back up???
does this occur while there is still water in there ?
no the tub is empty of all water, just the wash load is in there!
Check for a loose belt, should be fairly tight. If ok, if you have an amprobe, check the motor current while it’s doing it’s weird thing.
If current is stable, you might have bad spin bearings and a slipping clutch, check the clutch housing for heat.