Bad linear bearing/rod or misalignment?
I just finished assembling the MK2.5 upgrade and while I was running the calibration for X/Y skew and Z height I noticed a scratching/rattling noise coming from the x-axis (seems to be from the carriage). I have taken the back of the carriage off and when moving the bearings by hand the top two seem fine but the bottom one catches about every quarter turn if you rotate it on the rod. (I know this isn't how the bearings work but I assume that if they are good you should still be able to rotate them without much resistance). I'm wondering if anyone has a good way to know if it is the bearing that is bad or if there is just wear on the linear rod where the bearing had been riding for the last 800 hours of print time.
I also wonder if the noise could be coming from misalignment of the bearings. It seems like the back cover of the x carriage is a little strained when screwed on because of the left hotend fan and extruder motor wires having to squeeze behind it. Does anyone know how well it should fit and if that could be causing bearing misalignment? Also, the noise seems to go away or be reduced by loosening the screws that hold that cover on which is what makes me wonder about the bearing misalignment.
Edit: Just reassembled it and noticed that the sound goes away when the carriage is near the right side and gets louder near the middle. I also found that if I loosen the center screw in the carriage back the sound lessened dramatically.