I was a general machinist for several decades and have a sense of what I'm doing, but I am having trouble getting my Tri-powers to repeat. When I tighten up the gibs the servos just bog down, and when I loosen them up there is too much flex when changing direction in any axis. Even with tuned Mach III motor tunings and rigid setups my machines don't repeat. I bought these machines in 2008 and one has factory installed ball screws (ST108) and factory installed 4th axis servo (ST98S-4) I've been able to use them but I would like them to be more accurate. Any suggestions?