I just got off the phone with Christine at StoneMills. After looking through her inventory sheet she came up with three filters, one of which might be the UV filter I'm looking for. The first two are for the cls2000 but I'm thinking they might be the same filters used in the cls1000 and the cls1840 - "base filter...part #AA98340" and "heat protection filter...part #AA98429". They do have a UV filter (part #AD58304) but they're not sure which enlarger it's for. Anyone have a parts manual for either the 1840 or the 2000 so that I can positively ID these numbers? Thanks, frotog.