Gantry moves different distances on either side

Hello, I am relatively new to 3d printing. I got a Longer LK5 Pro about a year ago and I have a problem where the powered side of the gantry goes up the correct height, but the right lags behind, giving the gantry a “tilt”, which usually leaves unsatisfactory clearance and/or surface finish because of inconsistencies in the height of the nozzle itself. It is of note that it is only noticeable with relatively small amounts of z axis travel (the actual distance that they are apart is probably from .4 to 1 mm, but it is still enough to throw off the print), although I assume it is still there in larger movements. I tried experimenting with different belt tensions and changing the eccentric bolt on the gantry wheel, but nothing has really worked well. Is there a way I can fix this without making significant hardware modifications? Thanks in advance