replacing thurst bearings
Before you go much further, determine where the .0005 to .0007" is coming from. Is the lead screw moving or is the bearings moving. After the bearings are traped on the lead screw, then the bearings have to be trapped where they are installed. What I mean to say is, yes the screw is moving but are the bearings moving also.
If you have two bearings on the end of the screw, when they are properly preloaded, you should be able to grasp the bearings, one in each hand on the outer races and move them in opposite directions. The tighter they are, the better but, you should be able to just move them. (The outer race on one bearing clockwise and the outer race on the other bearing counter clockwise). You are testing to see how snug the outer races are pressed together.
It is quite simple when you do it but difficult to explain when you try to type it out.
If you need more explaination, let me know.
Regards Walt...