TDC Duo woes

[Tom Deering <tdeering@xxxxxxxxxxxx>]

Does anybody else use the TDC Duo projectors for MF projection?

I having vignetting trouble.  The cone of light it throws out does not
cover the entire MF slide.  I checked, and the condenser parts all appear
to be intact. They look like this, schematically

.lamp.    (|     x     |)     (|     .slide.     .lens.

where the x stands for the heat absorbing glass, and the |) and (| are the
three plano-convex condenser lenses.

Since this projector was made for both MF and 2x2 slides, does the
condenser have to be reconfigured somehow for MF slides?

And while I am asking, what bulb do you use in a model RP?  I have four for
these Duos and they have four different bulbs.  :^)

Thanks,

Tom