Kyle, Gerardo 

Today we continued looking for the leak(s) on the Y-mid turbo, and found it/one -> there is a 2 x 10-5 torr*L/sec (for helium) leak at the factory O-ring seal for the motor wiring feed through -> This is thought to be a very thin cross-sectioned O-ring between the square-flanged feed through and the turbo motor body -> This value of leak (if same for air) would account for the observed pressure rise for time periods this pump has remained idle but, not knowing the actual dimensions of the O-ring could also be accounted for by permeation etc...  -> to test, we moved the LD and helium to the X-mid turbo and observed no indication of a leak or permeation for the same application of helium -> it is not clear how serviceable this O-ring is -> it may be that it would have to be stretched over the square flange in lieu of desoldering motor wiring -ouch!