no sound, can barely hear it when volume is on full

Hi

I have a mpc2500, the mode button broke so i gave it to my dads friend to fix.
the mode button seems to work fine now but no sound (or extremely low sound) is coming from my mpc.
it is on a stereo output to a mixer, all the lines are open.
I have the same problem when as well when i hook up the headphones. i can hear faint noises when the volume is on full
I have tried the factory reset and also tried to change settings, even though i feel this is more than likely an internal problem i was hoping that it was some setting

does anyone have any idea, im going to give the mpc back to the person who fixed the mode button to get another look to see if anything slipped out of place when he was putting it back together
if anyone has any suggestions so i could point him in the right direction
that would be great
thanks

Theres a setting somewhere in the menus to adjust global output of the mpc, try that first