Braking gear- not engaging
 

Hello.
I bought a 1995 Volvo 940 turbo. Everything seems to work just fine, until you try to put it in park. For instance, I can shift the gear to park just fine, but it won't engage. I use the emergency brake to keep it from rolling. All the other gears work just fine.
Due to insufficient funds, I am going to try to get as much information and advice on how I can tackle this issue myself. So, if you can help me troubleshoot the "braking gear not engaging" problem, I would very much appreciate it.

P.S.= Sorry about the title, I should have typed "Parking gear..."