This would seem to be the first step in analyzing the problem. Get some regular VC filters and try them. If you get similar results, your enlarger is OK and you are either not developing correctly or you are misinterpreting the results. If your prints look OK, it's misinterpretation. If you get different results, the magenta filter in your enlarger has faded, and you will need to get a replacement. Magenta filters do that, and it may not be obvious to the eye.
Originally Posted by cliveh