Your cuts are pretty aggressive. 0.1" per pass on polycarbonate takes a lot of power to do. I suggest trying a much lighter touch and cut half the depth per cut (0.05") at half the speed. It's the cutting force that really brings out the slop in a machine. The cut quality will improve too.
Another thing you can try is to leave an offset on the part and either sand it off or use a final pass (or another cut file) to trim the part to final size. The lighter the touch, the better the cut, especially with a worn out machine.
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