2500 Output Malfunctioning

Audio through the left channel of both my headphone and stereo outputs have been going in and out recently, and usually stay out after about a min

I recently installed the xlcd screen from mpcparts.com and was very careful with handling my naked beat box so I don't think i damaged anything then but who knows

I'd rather fix this myself than pay extra for it. How can I determine where the problem is occurring and what parts need to be replaced or repaired?

I downloaded the service manual but am having trouble using it to help me identify the signal chain I am looking for.

this problem with the 2500 has been surfacing quite a bit...do search cuz I cant remember what the solution was if there was one. also I'd give mpcstuff, vst akai service and forat a a call and see what they say...worst case scenario new pcb board ? maybe volume pot gone bad ?