I just bought a used Shapeoko XL and the previous owner seemed to have improvised at times instead of following the instructions. The only unresolved issue is a noise when manually lowering spindle mount. It almost sounds like the belt is slipping, but I have tried tightening it and loosening it and with same result.
Please see this video:
There is no play in the assembly and the Z carriage runs smoothly on the rails. It only seems to happen at a specific point and occurs mostly with a faster movement.
Any suggestions as to what the issue is?