Maintanence:
Mr. Fixit. If you have some tools (nothing special), some fixit experience, you can do most or all of it yourself.
I haven’t needed to work on one of mine or my sons (4 total) in years (except normal head/capstan rollers clean/oil). I can do anything physical to them, but nothing electronic. These Teacs are built like tanks, the old grease and old belts turn to glue. 6 screws the case is off. Remove all the junk, new lithium grease, new belt, the brakes need to be adjusted, the height of the reel decks need to be raised/lowered to align the tape with the heads and avoid the tape rubbing on the reel edges.
Not always needed, but when apart I take the motors out, apart, clean moving parts and electrical contact points, lube, back together. Mark their screw positions and pay attention before removal and disassembly, just careful common sense.
resistor adjustors for ff and rewind speeds, tape tension for fwd and rev play speeds, ..... like an old carburetor idle speed and fuel mixture: one effects the other, take your time, wait, tiny adjust, wait ..... you will get it. also, like a carb, you make the adjustments while it is running.
I find heads stay aligned, and I have even replaced the entire plate with pre-mounted heads with success. Alignment perfection needs a professional. Worn heads can be found or re-conditioned.