Z-level, PLA not sticking, PEI damage  

Z-level, PLA not sticking, PEI damage

Oh boy.

So I got my Prusa i3 Mk2 kit a couple weeks ago and assembled it over that weekend. First print was FLAWLESS. Second and third prints were flawless as well. I moved the printer from my living room the bedroom, must've bumped the PINDA probe and had some z-level issues. Adjusted the probe, ran XYZ calibration again, ran the calibration gcode, looked away for a moment, returned to a big zig zag burned into half of my PEI sheet.

Damn; learning some hard lessons. I sanded down the PEI sheet as much as I could to remove some of the surface inconsistency, but there's still a deep zig-zag trench running right in the middle of my bed. I've placed an order for two new PEI sheets. In the meantime, I've been trying to dial in prints and they are not cooperating anymore.

I've adjusted the PINDA probe over and over, ran XYZ calibration, piece of paper, whole nine yards. The calibration model is unusable without offsetting due to the trench in the sheet of the same shape. Even with other models, PLA will simply not fully stick to the bed anymore, and definitely won't stick anywhere near the trench due to the bed being deeper there. Additionally, every print I have to lower the Z-adjust by another ~.07mm to get even partial sticking, until eventually I get to -1mm and have to start all over. Long story short, I have not had a successful print in two weeks now. Really disappointing because the first several prints were INCREDIBLE!

Also, I moved my filament spool to a set of TUSH ball bearing rollers sitting on the table next to the printer, rather than have it be mounted above. Just FYI.

Theories:
* The deformed surface of the PEI is just a game breaker.
* I sanded the PEI too much.
* I'm noticing inconsistencies in the thickness of PLA strands pulled off the printer; sometimes they come out bumpy. Moisture in the PLA affecting bed adhesion?
* Z-level drifting somehow

It seems like a lot of factors are probably screwing up my prints. Any advice would be super rad. Should I just not bother until I've replaced the PEI sheet and eliminated that obvious issue? Thanks for your time.