Adhesion issues with MMU prints, bed adjustment settings not adequate to get level  

Adhesion issues with MMU prints, bed adjustment settings not adequate to get level

This is an upgrade from a mk3s+ to a 3.5, so I have the new bed brackets vs the spacers. 

After calibrating, my live z is at -1.900.  This produces a good benchy reliably, and I've done a few other prints with good results. 

I've done 5 attempts on the sheep with the MMU3 and not one of them has been able to stay stuck long enough to finish.  Both the sheep and the purge block have come loose, though usually not both in the same print.  I have tried multiple heatbed sheets, cleaned all with soap and water, IPA.  I assume I'd see some failures with single filament prints eventually as well, and something about the filament changes and purging are exacerbating the problem.

This is what I'm looking at, initial no bed level adjustments

And here I am with +25 on the right, very slight improvement. 

The problem is, with 25 right, the center is no longer acceptable.  The fill has gaps between the lines/not squished properly

I've iteratively gone all the way up to +100 right, and while it does get better, it's still not there.

Bad center layer

Right +100

I'm not sure where to go from here.  I'd be willing to sacrifice the far edge of my printable area if I could get MMU prints to stick as well.

I've read about people using nylock to better control the level of the bed, but haven't seen that applied to a 3.5 yet.