Audio Dropping out of Channel

MPC500 seems to work fine, until it spontaneously loses audio in the left channel. This happens with headphones and speakers. Also, when this happens only one sample or track will play at a time.

The most recent incident occurred in the middle of playing back a recording. Operation was fine until the glitch, but now the malfunction seems permanent.

I bought this thing on eBay and have had it for just a few days. Waiting on response from the seller, but I thought I'd check for advice here in case others have experienced similar problem.

Thanks for any help/insights.

have you tried a different sequence to make sure its not programmed changes you are experiencing. Or does it do it to every sequence? Turn it off then on, make new sequence with samples you know are ok. loop sequence and play. does it have same problem?? Could be a few diferent things, i rekon IMHO it MIGHT NOT be hardware issue as it is happening in both headphones and output at same time and that seems like the way its set up. ie, some sampling programme is set to mono or some effect or filter might be kicking in. So restart, make fresh new sequence, does not have to sound good, loop it and sit back and see if it happens again. if it does then yes it might be broken.....but try what i said and see.You might just have run out of memory, you do not give enough info to really tell.

Thanks for your reply. Sequence was playing fine until the issue occurred, so it's not programmed to drop out. Here are some more details:

-Connected to MPC through phones output via 1/8" to 1/4" adapter. Both cable and adapter are stereo.

-Samples recorded from turntable to computer. All stereo WAV files. Some samples from SP1200 emulator kit also had same issue, although that was a different sequence on a separate occasion.

-Problem happens whether listening through headphones or through my speakers. Connected to receiver the same way - stereo 1/8" to 1/4" adapter. Not ideal clearly, but it's a temp set up just to test the device until I can get proper cables for the lines out. Nevertheless, I should be able to monitor my output via the phones jack without having this issue.

-Have turned off/on many times. Updated to latest firmware/OS shortly after receiving item.

-The problems doesn't seem to happen as much with the factory samples and sequences, but then again I haven't listened to them nearly as much.

-If I pull the jack out halfway, the sound seems to switch to the left channel, but it's very weak and it drops out of the right channel.

-I'm pretty sure the issue has occurred after I've applied effects. What's strange is that it doesn't happen instantly, and even after I delete those tracks the sequence continues to have the problem. Usually it's only two tracks - drums on one and a phrase on the other.

-Before glitch, the tracks and samples play simultaneously, as they should. After the glitch, the audio from only one sample will play at a time (and only through the right channel). It's like it happens in the middle of looping the playback, so I know it's not something like a mute group or polyphony setting causing the problem.

I don't know enough about audio to say for certain, but it seems to me like the issue is either an intermittent phones output or a connectivity problem with the 1/8" to 1/4" adapter (which was brand new). The seller told me he's never had the issue before, but he also confessed that he didn't use the phones much.