Originally Posted by peri24
This will sound silly but... you must try changing the bulb. At one point, following customer reports of similar difficulties with their equipment, I conducted some empirical bulb tests and became apparent that the bulbs lost energy in the shorter spectra long before they lost any apparent brightness. Changing the bulb out for a new one can have a dramatic effect on the available contrast. You don't want to know how hard it is to find a fresh bulb that will actually produce G5.
All of the above however presumes that you understand the function of the white light / focus lever and that you have the filters in place. You do actually see a noticeable change in the color of the image as you rotate the filter knob from low to high contrast?