Audio Systems: Ford 96 F150 truck radio not working, four holes, cassette radio

Question
My stereo is a cassette/radio system. The Radio part has stopped working. It comes on by itself when it's really cold or really hot and sometimes if I bang the dashboard with my fist. The cassette deck works no problem. I think it's a loose wire or bad solder joint. I'd like to remove the stereo but can't figure out how. My unit has four holes, one in each corner of the face plate. Is it worth fixing and if not how could i remove it to install a new unit? Any help would be appreciated.

Answer
the problem is in the tunner the capacitors go bad and leak
time to replace the radio
here is the link on how to remove the radio

http://www.installdr.com/InstallDocs/FLM/PDF/356037.pdf

this is the link for the radio if the radio don't have cd button is cheaper $80.00 you have to call them

http://www.partydown.com/subcat166.htm