@dc42 @alankilian @Phaedrux
Thanks for all the help. it is working now.
What I discovered:
The reason my AGC was so good was that the magnet was almost touching the hall-effect sensor. In fact, when I disassembled the MFM I found that the shaft from the hob gear was scratching a nice circle on the top of the hall-effect sensor. I believe this was causing the magnet to turn intermittently.
What I did:
I reprinted the housing using .06mm layers and gradually sanded it down until I got 90 agc. I then moved my MFM mount down about 50mm and added PTFE tubes on the enter and exit. I'm printing a XYZ calibration cube at the moment and here is my M591 D0:
Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 24.80mm/rev, allow 10% to 190%, check every 10.0mm, version 3, mag 131 agc 91, measured sensitivity 27.16mm/rev, min 89% max 103% over 1234.5mm
Again thanks for all the help.