@michael-petitclerc The shift occurs only on Y-axis.
I then checked the Z-screws: Right: -1.52mm Left: -1.58mm
The Z-screws are in in the correct position. This is how they appear with the gantry at home point.

Definitely use z-lift 0.2 and 3x3 bed leveling to reduce nozzle friction against the printed object.

This Pulse DDD printer of mine has made thousands of successful prints. Out of the blue the layers would shift one way then another without a clue as to what's going on.

When the layers started to shift, there was no new code, not even the Matercontrol was updated.

I ran through the checklist with hopes of discovering something mechanical. Nothing appeared out of line. Meaning, everything was tight and in solid condition to print.

The last thing I tried was connecting to a different computer and using the latest release of Mattercontrol. There were no good results, the layer shift was still there.

One niche discovery is small simple prints will print successfully on the center of the bed but not else ware. The complex prints suffer shifting error in the early layers every time.

What's the next level of testing to determine the error?

Having recently replaced a thermistor, I found myself reorganizing a bundle of wire for the installment. Since the thermistor replacement procedure the extruder fan is non responsive.
(I have verified the fan to be a functional fan.)
If I had plugged the fan into the wrong terminal of the board, how would I know which one is the correct terminal?? Where would the wiring information for a Pulse printer be offered?