Why oh Y are you killing me  

Why oh Y are you killing me

I recently changed nozzles and since then I have been unable to pass Y-axis calibration.  I have had this happen before and have been able to fix it by making adjustments to the bearings.  I have not had such luck this time.  I have now taken it out of its enclosure 37 times and adjusted the bearings and tightened the screws everywhere and gone through everything I can think of.  It looks exactly like the picture shown in the troubleshooting guide and is exactly 46.5mm apart, as it is supposed to be.  It prints perfectly, but this error before every print is annoying and the printer really should be able to run a successful calibration.  I have not gone to Prusa support yet, wanted to see if you all had any answers that might help first.  Thanks in advance for any possible solutions.