We are a group that have made a community darkroom and acquired a wonderful Ilford Multigrade 500 H Enlarger and Control System but there are parts missing. Those are the three light mixing boxes and register plates. Does anyone have these parts or could tell us where we could buy them? Our enlarger head is; Durst Laborator 1200. The three light mixing boxes and register plates would be those for 4 x 5 inch film, 35 mm films and 6 x 7 cm or 6x9 cm films.