My Teac 3340S records only on channel 2
All four channels and VU meters working when mikes plugged in and selectors set to "source"; red record lamps light up on channels 2, 3 and 4. (I have not tried changing the bulb yet)
Only channel 2 gives an output when selectors set to "tape"
Also, "pause " button puts deck into rewind mode not pause!
a lot of times the transistors go bad in teac decks. A good audio shop can fix it up, the transistors can be replaced with off the shelf types, and it will work quite well again.
Also, replace the belts.