First row about .5 mm high  

First row about .5 mm high

About 6 months ago my Prusa MK2 printer started printing 'too high' on each subsequent print job. To get the first layer to stick I had to use the Live Z command to lower the head about .5 mm at the start of every job. I have loaded firmware 3.2.3 and nothing has changed with that firmware. (I'm contemplating loading a very old firmware and seeing if this was induced with firmware).

It doesn't matter who/what program did the slicing, it's always too high.

I have found a workaround that is working, but that involves sending the following command before each print.

G28 Z    #lowers head until it hits the deck
G92 Z0   #reset position of Z to 0
M500     #save this in EEPROM

However, I still have to do this in front of each print job, which makes me thing that something's not right with the EEPROM save, or something corrupts this location.

Does anyone have any thoughts on this issue?