[Timo]

That was the first thing I thought of asking, ie. if you smoked.

Smoke gets everywhere. It penetrates through cracks and grimes up all the internal electronics.

That's why people state "Non smoking studio use only" as a plus when they're selling gear.

And it's doing your lungs no favours either.

I tend to clean/dust all my gear with a dyson hoover with the soft-brush attachment. Or a funky little retractable anti-static brush thingy.

I have an Indigo (v1), and all the pots feel fairly uniform in their resistance when tweaking them. For example, the "Cutoff" knob feels as stiff as the rest. The main Program (parameter) knob is a tad dodgy in that it wobbles a touch, but I'm replacing that soon for that reason.