I am considering purchasing a Beseler 45MXII enlarger with a cold light head, it says on it *Beseler 45MB cold light head, Cat. # 4785. I have been told it's quite old, older than the enlarger. Can you find lamps for this head if the one in it blows? What is the pedigree of this head, is it a Beseler, an Aristo, or?