Have you tried the ol' electric tape trick? If you remove the dosing star from the chamber and give each arm a folded strip of electrical tape, such that inside is sticky and the outside is not sticky, such that the electrical tape acts as a kind of "brush" to help "sweep" the chamber clean, that might help. At least it works well with Mazzer-type dosers.
I am admittedly not super-familiar with the Anfim build-out, but I would be wary of tightening the dosing star assembly, as with most dosing chambers, tightening or loosening that component is used to increase or decrease the actual dose of each pull - such that the tighter you make it, the smaller each dose is? Again, this may be woefully inaccurate w/r/t Anfim buildouts.
But try the electrical tape!
I have the electrical tape mod on my super jolly, it works ok(all though i didnt spend a ton of time perfecting it) heres a thought, why dont you just switch your regular and decaf grinder. That way the grinder you use more often is cleaner and more accurate weight wise, till you can figure out a way to "fix" the other one.
I also have a obel bregant(also know as a la pavoni zip among other names) and it seems to clear the dosing chamber way cleaner than the super jolly. I originally bought it to resale, but know im might keep that instead.
Are you sure it's assembled correctly? I'd say take it apart and try fixing it again. If all the parts are in their right places it should definitely sweep clean despite the settings.
You can tighten the star by rotating the screw clockwise.