Hello you all!,
I recently purchased a Durst Laborator 900 enlarger (very big and heavy!), but I have no manual.

Although the basic adjustments and functions are the same as other enlargers, there are a couple of things which escape me! Can someone please help me to understand them?

For instance:

.- At the base of the "mast" there is a "focus variator" (with two wheels) and a mm scale. It seems to me something related to the use of easels or such things... as the enlarger seems to keep focus even if the head is moved... in order to adjust the height of the easel surface...

.- The mast has different scales... (4 in total) does any scale has something to do with exposure compensation depending on the height of the head?.

.- Do you read such scales from below the head? (what do you use for reference?).

.- The 50mm lens aperture is sticky and would like to clean it. It is holded by a BIMAPLA holder. May I just unwind it (difficult to access it as it is very protruded) or have to dismantle the whole bimapla?...

Well I have more questions, but I don't want to bother you too much! .

Trying to post a pitcture...

Best wishes!

Juan Miguel