I have been running the eBay 6040 for 4 months now and it has finally developed a major problem.

My x-axis is jamming up when it gets near the middle of the axis. It causes the whole gantry to jump as it passes across this area and results in a jagged finish on the work piece which is unusable.
It only happens when travelling in one direction - pulling towards the stepper (as opposed to pushing away).
It seems to happen at slightly different points along the axis each time I try to recreate the problem so hopefully it's fixable.
I would guess that it has got dust inside the bearing. I may have caused this by applying spray grease to the ball screw several weeks ago.
I am tempted to strip it down and clean everything but this will be a big job that is a bit out of my league.
Any advice would be greatly appreciated.

Thanks,
Kevin.