sounds kinda obvious I know but have you tried cleaning the sliding groove?
I may be wrong on picturing it in my head, the part i mean, but if you can clean it, wipe with isoprop and then lubricate it. you may find its just needed that… a little TLC 😉
same type thing happens with the blade not spinning properly in the blade holder. clean and lubricate, sorted.
obviously there are lots of reasons this type thing can happen but eliminate the easy ones first. :smiles: