If you can come across a "worm track" diagram for the case, you can air check friction elements by using a rubber tip air gun and ~ 100 PSI air. ( sometimes you need to make a plate that covers an entire track in order to apply air. )

You should hear a solid "thunk" when adding air, you might get a slight hiss. If you can't make any pressure and hear a large air leak, either sealing rings or piston seals have failed.