Hello !
I own a Durst enlarger with a color head produced in the 70's. The enlarger had professional use in a pro lab, when I got the head it had spent a couple of decades in an attic and was filled with everything from dust to feathers...
I cleaned and lubricated the head and just dusted the filters. I thought they had worn out so bought replacement from Focal Point (I think they are not in business anymore ? ) and switched them. Having the old filters out, I tried to clean them using optical cleaner (like the Kodak stuff) and was surprised to get them back, the fading had vanished (it was cooked dirt...) so I'm thinking putting them back on. (I did not because I use the head very seldom and it is a PITA to reach the filter path..
So you may have a pleasant surprise by cleaning. But buy replacement before cleaning because YMMV ...