Cutting gets shallower then deeper as the spindles travels to the right

My Spindle gets shallower as it travels right for about 8-9 inches then gets deeper it goes right. It ends up deeper than when it began. It used to only get deeper but now it gets shallower then deeper. I have tightened the set screws on the z-axis and checked to make sure that nothing is physically wrong with the rail. I’ve put a carpenters square along the top of the rail to see if it’s bent somehow but it all looks good and level. I have been just creating projects where I can do them in two or three stages if the carving is over certain lengths. This is getting frustrating though. I still like the machine and have created some very beautiful pieces but doing them in two or three stages just takes too much time. Any help or suggestions would be helpful.


Have you flattened your waste board?

I lifted one edge of the waste board to make the cuts more even ( .002" difference from left end to the right end). It was working very very well for about a month or so after that and it now rises for about 8 or 9 inches then drops back down as it travels across the workspace. It finishes even deeper at the far right than it began at the far left. I measured the distance from the waste board to the rail and it seems fine. It’s off by just a couple of thousandths. At one point the machine freaked out a bit when I pushed the stop button because I realized I had misspelled something. The next time I used it the Y-axis was exactly opposite of what it should have been. I just turned it off and turned it back on and it worked fine. I attributed it to some software thing. I’ve heard of that happening before.