Audio Systems: Cassette ejects from Blaupunkt soon after inserting, plastic wheels, cassette deck

Question
I have a Stuttgart Blaupunkt from a late eighties Porsche (I think) in my car, and the cassette deck keeps ejecting the cassette after about 10 seconds.  The only way I can get to play cassettes, is to turn the unit off right after inserting the cassette.  When I turn it back on, it will play the cassette with out ejecting it.

I love the radio otherwise, and wouldn't want to buy another, but this bugs me.

Answer
if you open the cassette deck and remove from radio change the belts  some times this solves the problem but most of the times there is a sensor in the back of the cassette
there are two big white plastic wheels they have sensors to stop the tape and eject if the tape gets stuck or opend
most likely you are not going to find this sensor so just solder the 2 connections together and it will work  the only problem is that when the tapes finish one side is not going to switch to side B by itself you have to press the button