Not sure how else to describe the flavors I've been getting lately from a couple differently blends. It's a cardboardy flavor i've previously associated with stale coffees, which i know these are not.
I've tried varying temp and dose and can't seem to get rid of the underlying flavors. Have done a cleaning with Cafiza too.
Now that i think about it, i think the Vario could use a cleaning too.

I know i'm not giving much to go by, but any help is appreciated.

Try giving your machine a good clean as well.
Pull the shower screen and clean/replace if needed, descale, etc..
Then as you say, take the grinder apart and give it a good clean as well.

Vario thoroughly cleaned and I think it may have addressed the issue. Testing will continue.

well, it appears that i just had a case of dirty grinder...how embarrassing that i didn't check that first!
lesson learned.