MPC2500 Main output and Headphone Problem (VERY LOW OUTPUT)

Hi all. Having major Main Output and Headphones Issues!!!!

I just bought used 2500 (my first one). Started playing with the samples - all was well with the Main Output.... UNTIL...I purchased the new JJOSXL April 2013 version, installed it, everything seemed fine...then,

1. recorded sample from turntable into MPC
2. chopped the samples up (non-destructive) with Chop function
samples were fine at that point - nice and loud
3. pressed Do IT
4. 3 seconds later my Main Output drastically reduced in volume!!!!!!

I've checked all internal setting for all outputs, FX etc.
Checked the cabling - used different cables - different setups with my DJ Mixer and Mbox and cant seem to find the problem. The levels are still very low - to the point of cranking it all the way up on MP and still very VERY low.

I then tried to re-instal factory AKAI OS....Still the problem is there.
Someone please help.... i am desperate!

Any info would be much appreciated!

Thanks,
Ruski

UPDATE!
Not too sure if JJOSXL has caused the issue.
I've tried re-installing AKAI OS - the issue went away for couple of minutes -
- then I reloaded new Program with Samples - start pressing/tapping pads with samples loaded onto them the volume freaks out and drops drastically again.
Not sure if it's OS or hardware issues here.
If anyone experienced anything like this before please let me know.
Cheers

Its possible your volume knob may be going bad. This is very common with the MPC 2500. I've experienced this along with the left channel going out.

As a test, rout the the sample to one of the individual outputs and see if you can hear it with normal volume. If you can, this is a good indicator that you need to replace the volume knob.

You will need a soldering kit and new knob. Knob cost 16 bucks at mpcstuff.com.

Good luck.