Epifluorescence filter issues

I’m using a Zeiss Axioplan 2 (the older 5-cube model) to view GFP-tagged neurons. I got a worm strain with cyan/yellow tagged neurons (EM800) so I need a different filter set.

I got a used filter set (Chroma 51017) and installed it in a cube using the filter orientations listed on their website (arrows pointing into cube, dichroic coated side down).

Instead of seeing shiny neurons on a dark field, I see a solid bright lime-green field. It looks more or less the same on the agarose pad or bare slide glass. The light coming out the lens is violet (yellow when I switched the ex/em filters).

I’ve tried flipping the dichroic and all permutations of flipped/switched filters with no change. I’m wondering if the dichroic actually belongs to another filter set.

I’m at home now, so I also need to try this with a dry lens in case it’s something in the oil drop on the 40X oil immersion lens. (Now that would be a truly easy fix!) EDIT: I viewed a standard Turtox teaching slide with the 20X air objective, and this wasn’t any better.

All the folks who sold me this gear are on vacation until it would be too late to include results in my poster for Model Organisms 2.

At least I have some results using my GFP strains, but one has too many neurons tagged to tell them apart, so it provides only weak support for my hypothesis.

I’d be grateful for any assistance.