OK Russ, let's start with the basics. I use my B-77II daily, so I'll have a go at it. Are the heads clean? Did you try another KNOWN good tape? Is the tape threaded correctly? When listening, the input selector should be in the TAPE position. On the back of the machine, there are screwdriver level adjustments for each channel that control the output. Are these all the way counter clockwise? If so, that's your problem. Make sure they are set at about the 2 or 3 o'clock position when facing them. Might there be an audio card partially out of it's internal socket? To check, pop the case off the machine. Along the bottom are the various audio, bias, preamplifier, etc. cards. Make sure each one is securely seated in it's socket. If the machine has been handled roughly or knocked around, it is not inconceivable for these to become loose. If none of these things gets you any audio, the recorder will likely need professional servicing. Let us know how you make out. Craig