I have just finished a rebuild on a York LTD-126 compressor, not my first one. This time I have a problem. The input shaft will not turn if the system is in a vacuum, at atmospheric pressure it seems tight to start movement, but as it turns it gets easier. When under nitrogen pressure above 3-4#s it moves freely. All the tolerances are to the York manual for thrust (low and high speed) run out on the impeller is .0005" and the eye is .0000. I made sure it kept turning free during assembly. HELP! please. -GEO