mpc2000xl issue (flicker on left input channel?)

Hi,

I finally reacived my mpc 2000xl today, everything seems to be working great except for one thing that is confusing me. When I check the meters for sampling an analouge signal, the left channel is flickering?

the right one remains to the bottom as it should...
the left one has 1 constant "block" symbol, and a second "block" which is flickering.

anyone familiar with this problem? I haven't updated the os (currently 1.12) ... but I think it's a bit far fetched that that would be the problem....

note: the block(s) disappear if I switch to digital, so it can't be some graphical bug... I think?

...could it have to do with that there could be some dirt on the contact-surface for the left in or something? or is it supposed to be like that?

its probably noise from something....

from what...?

I've tried it both without and with cables goin' into the machine - in both cases I get the same flicker on the left channel...

I was thinking first of that it could be some kind of groundloop or something, but... why would that only appear on the left channel - I've tried moving around the machine aswell - no difference.