Some replies to my post on the selenium intensified neg have suggested that I have a 'cold spot' in the corners of my enlarger. I have looked at this and find something akin to vignetting on the top corners (see attached-phonecams do have a use !) I use an 80mm lens (Nikor) so do not believe this to be a problem and have taken the condensor out, cleaned it, tried it upside down etc. to see if something is amis but no improvement. Given that the Axomat is a very simple enlarger the only other possibility is the bulb which is in it. It's probably a small globe household bulb.
Any ideas PLEASE ?