I figured out that my new PEI sheet has a ridge around the perimeter. I decided to try and deck it instead of removing it to fix.
I basically remixed this to suit Eustathios- https://www.thingiverse.com/thing:2075490
I modded the sandpaper holder to take an M7 bolt instead, so to mount to the E3D heat sink.
The carriage supports the bottom fins of the heatsink, so I am not too concerned about the business end moving laterally under load.
Here are some pics and vids of my progress so far in case anyone is interested.
If you look at the perimeter of the sheet, you will notice the lighter color where the top edges have been sanded off. So far I am taking 0.01/pass, I am 9 passes in, or about -0.09 from where I started.
I will keep dropping images and videos as I go. Its at a seemingly tectonic pace so don’t hold your breath.
EDIT: here is a pic of progress- what is interesting is the ghosting of past prints in the center.