All of a sudden the filter knobs on line 3&4 are giving problems. I am not sure if the deck took a hit during transportation.
The filter is in centered position but the will suddenly activate a HPF until i fiddle with the knob, twisting it and placing it back to centered position. Then the track would sound fine only for a few moment until it does it again. Also, it seems for line 3, even at center position a little filter is activated and track sounds normal at 1oclock position.
I do not have any paperwork or box for this deck anymore
Where are you located? If you are comfortable with a soldering iron, it could be an easy fix (replacing the pot). If not, please take it to a repair shop.