Leon, could I ask you - with how many lenses is this problem happening? Have you previously had good results with these? If a fine-quality lens delivers duff performance but looks OK, this usually points to its having had a generous thumping, leading to misalignment.

I once had an f3.5 50 mm Leitz Elmar, made just after the war, which looked totally mint. I even spent money having a small scratch polished out and looked forward to using a perfect specimen of a legendary lens. The results was very poor, I sent it to several expert repairmen for a collimation check, it turned out the lens had been a dog since the day it was made! Probably an inaccuracy in the basic grinding of the elements, which you really wouldn't expect of Leitz (or Zeiss!).