It's only logical that a fan loses efficiency as it ages and airborne crap (technical term) accumulates on the insides of the fan. Are we talking 2%-5% loss of efficiency or are we possibly talking 10% (more?).
I have inherited a Trane Voyager that I'm having a static problem with, I am down about 15% from when the unit was first commissioned, duct work looks tight and i am tempted to re-sheave, just wondered if there was any insight from the group, before i do anything. The consensus among my Tech friends is that it would only have negligible affect, is there any reference material out there?