Bad Tuner on Sony REC-800

My radio tuner went out on my Sony car stereo.  At first i thought it was was the antenna or adapter but i installed another radio and it worked fine.  I never heard of a tuner going bad on a car stereo.  Everything else works fine like the MD and the Cd player,  i just cant tune into any stations with out getting all static.  Is there any way i can repair this?  is there a part or connection i can check inside the radio?   Please let me know at entourage699@yahoo.com or anderson01@ameritech.net   Thanks

I do have the skills to fix it but i am not sure where to start.  I just thought it was a little strange that a tuner went out on the stereo and everything else works.  i never heard of anything like that.  The last thing i want to do is take it in to a shop