Just another source of confusion, at school we have Omega enlargers I think, not sure the model. but they have a knob to engage the filter or disengage for focusing, three color knobs (c, m, y), the aperture on the lens, and then there's a fourth knob next to the three color filter knobs. I'm assuming this adds some sort of diffusion but it darkens the image on the baseboard significantly. It sounds like your problem lies in extreme overexposure at the enlarging stage and I know from experience (I'm new to color too) that there are about a million mistakes to make.