"Loose Connection" (as is the probable case in many products) is one of the things one should first check when trouble-shooting a product where a problem 'appears' to be happening randomly (especially occuring on/off ... etc).
To those with LEFT channel output problems...
* Does this also occur on the RIGHT (at anytime)
* Does this also occur if you route the output to any of the other outputs 1-4?
* Does this occure only for STYLE PLAY or PLAYER (MIDI, MP3, WAVE) as well?
* Do you have a 'sequence' of operations/buttons pushed to achieve this?
Answers to the above would be helpful in resolving this if it turns out to be a softwre 'glitch'.
Thanks,
AJ