Thank you AgX and ic-racer for the input, I appreciate your help.
AgX, these are very useful tips. I still cannot imagine how the autofocus can operate by purely mechanical means, but the design of various levers and shafts on the left side of the enlarger would indeed support what you are saying. Knowing this, I'll try and make it operate in autofocus once again; first I need to do some cleaning to my darkroom-to-be.
Strangely, I have not experienced any problems with changing lenses; changing of the film holder, on the other hand, was challenging .
Once again, thank you very much. And hope to hear more about this enlarger from other people too.