weird phasing or compression problem

Hi there
So im getting some sort of weird phasing on my mpc 1000
When i write out a structure that is reasonably long it has certain bits that seem to be louder almost like there s a compressor on certain bits
I've checked the master f.X channel turned it to off
Thought it might be f.X on mixer but wasn't that
Can't figure it out
Anyone experienced anything like this

there have been a number of posts like this in legacy sections. for most it seemed to be a faulty volume pot which needed to be replaced and the issue was fixed. beyond that it could be a damaged connection/contact with/on the outboard. does it only happen on the main outs? or everywhere?