pete4eyes yeah I had the same issue with the inner diameter being slightly too small and causing a tilt. I tried best to centre it using foil, checked with the marker method and although alignment seemed okay I didn’t notice a major difference between them and the Italmills so in the end switched back.
It’s an annoyingly slight difference in sizes. As you say filling the inside burr surface should do the job otherwise if you can find something to add some height to where it sits on the bottom burr holder ever so slightly that could also fix it.
This may work if it’s thick enough, but I haven’t tried it, just going by pictures: https://www.etsy.com/listing/1251632818/df64-burr-gasket