Hi all, I have 2 older TASCAM 242 (the early tan version), 4 track cassette decks and channel 1 will not record on both of them. They play back pre recorded tapes fine but they don't see a mic or instrument input signal, the meter for that channel does not show a input signal but shows a playback signal. Am i missing something here? 2 machines with the same problem? Blown input preamp i guess but it just seems strange both machines woould nave the same issues with the same channel. Hidden magic switch? Thanks in advance!