I've noticed this black oily substance coming off my CLEAN dispersion block for my BDB (It's a very lightweight metal substance, not brass), I can't help but think it's negatively impacting the flavor of my coffee. I was wondering if anyone knows if a standard block would fit without clearance issues, this one is grossing me out so much that I've switched to pour overs.

I've also noticed water pulled from the group has a weird taste, I can't really put my finger on it.

I'm stumped. I guess you could run a few cleaning cycles with the tablets to see if that clears it, but you've likely tried that already.

Do you have the 900 or the 920?

On my older 900 (I think it was the A model) I did have to take the screen off and the bakelite (?) piece behind it off, clean everything and replace the white gasket: they had gotten pretty dirty and the cleaning cycle wasn't helping. But this was the oldest version, where lots of stuff would seep and gunk up the seal area. I don't recall it being oily or metallic, but I don't recall it not being those, either. I mainly recall being grossed out.

It may be bakelite, I've soaked it in cafiza, so that might've messed up the coating.. which is what might be rubbing off. I've backflushed about 5 times in a day to no avail.