[jayceebee]

If it only happens in playback or record mode then it's highly likely to be associated with the takeup. Remove the top cover and watch the takeup reel to see if any tape starts to spill into the machine or if the reel speed is erratic. You may find you have to do this in a darkened room to prevent ambient light triggering the tape end sensors.

There is an optical sensor under the reel which detects loss of rotation, if no pulses are detected from the sensor for a set number of seconds then the Mechacon will shut down the machine in an attempt to prevent damage to the tape.

I'm afraid I don't remember if this model has a takeup clutch arrangement or if the takeup reel is driven by the reel motor and idler.

John.