84' Toyota Cressida - Trans Issues

I just bought a Toyota Cressida and it has some transmission issues.

It will not go in reverse.
It will go forward in Park, Reverse, Neutral, Drive, L1, L2 - Therefore as soon as it is started if you do not have the brake on good. YOU GO FORWARD...

Can someone please tell me what could be causing this to happen. And some suggestions on what to check an how to go about fixing it...

PLEASE Do not reply with... Bad Transmission.. Need a new one.

Without giving me some details about what could be causing this issues... Because their has to be someone disconnected, not plugged in, or not working to allow the car to move forward as soon as it is started...

Thanks in advance.....

Respectfully,
Perry S.