This is a Reichert Diapan. The Diapan (and it's little brother, the Neopan) have an unusual fine focusing mechanism that is actuated by angling the coarse focus controls about a vertical axis. Manuals are a bit tricky to obtain, but it is otherwise not an overly-complicated microscope.
The built-in illumination system (with 12V halogen lamp, focusable collector lens , field iris and filter wheel) is really the major difference between the Diapan and Neopan. (I notice you are missing a portion of the lamp holder)
wrt Phase contrast adjustment - here is a link to the Reichert phase contrast manual (albeit in combination with the more elaborate Zetopan model - but the concepts are the same) http://www.science-i...al_Contrast.pdf
As far as I can make out, I only recognize one of the objectives as a Reichert phase objective (red band) and if you look at it closely you will see the number 3 on it. This number indicates that this objective is to be used with the condenser in selecting the #3 phase ring. To align the phase rings (as per the linked manual above), it is easiest to do so with a phase telescope in place of one of the eyepieces. These are regularly available on eBay such as this listing here:https://www.ebay.com...353.m1438.l2649.
Hope that helps