Krokus 66 enlarger - how do you remove the lens?

Recently obtained another enlarger. It's exceptionally dusty so I need to dismantle and clean it. Condenser lenses come out easily enough, but the focusing lens doesn't have any obvious methods for removal. Read that it was M42 so tried turning it, but nothing seemed to happen there. Anyone got any advice? Cheers

Unless it's been modified by previous user, there should be m42 thread. Use WD40 or something like that.