A Wratten 82A or 82B filter will tame the yellow cast. I'm not sure which one, I haven't bought one to try out yet, but was playing around with some slides I shot on the CR200 in GIMP with a color temperature changing filter I found and it seemed like 82B would be more likely to fix the yellow. 82A absorbs 1/3 stop and 82B absorbs 2/3 stop.