Hi, my General Electric 3-5259A is in getting the cassette deck and FM Stereo seen to. The bloke did say that due to me not being able to provide him with a schematic, it will not be easy for him to diagnose the Stereo problem and he may not be able to do it. His trained eye noticed a slack belt on the deck which I thought was fine (I've seen a lot slacker), but the problem is the auto-stop. It won't allow the deck to run, it just clicks off. When the deck runs temporarily before clicking off, the belt does move everything round. I hope he can fix my Blockbuster. The FM Stereo issue is the main one. Wish me luck!
j/k all the best 
but fingers crossed they can sort it. If ever you get stuck, I've managed to restore FM stereo to the TEC 878RR and that and I'm not far from you in sunny Wigan 
I thought you owned it before Lav. Yeah, if the guy can't fix the FM, I may be calling at yours! 
Good Luck.