I have resurrected a plain B&W enlarger with a filter drawer above the lens. I have been given a set of filters to fit but there seems to be an odd filter out. From Gd 00 to Gd4 are OK but Gd 4.5 is a very pale amber colour although it is marked as being that grade. Gd 4 and Gd 5 are both a magenta colour. The change of colour just looks very odd. Any thoughts? If I use my LPL7700 enlarger with a colour head to print B&W, Gd 4.5 even using the dual filter recommendation the colour is very different and quite a lot denser.