Tape auto-stop won't stop

[Northerner]

Got myself a little Sharp QT27 for nothing but it has a couple of issues.

When you press play the auto stop immediately kicks in and stops it. The belts are good and ff and rew work fine. I've had the deck out but nothing jumps out at me as the cause. It's clean and everything moves freely.

I'm sure there's a cause that's obvious to those who know a lot more than me!...any clues where I should start?

 

[Mark GF-575]

I've got a Hitachi TRK 22E that does the same on the 2nd deck. I find if I press play and hold it for a few seconds it sorts itself out. Or just press play, stop, fwd, rew alot.