Whenever I thoroughly clean my enlarger - I do it out in the open, on a sunny day so that I can check every nook and cranny. Before I take it indoors I use an anti-static gun (pietzo crystal) all over. Then I cover the entire enlarging head and lamp assembly with an air tight plastic bag. I only take the bag off before I start enlarging and return it when finished. I assume you have cleaned all the glass surfaces with methylated spirit.(posted 9590 days ago)