So, here we are with some more details of my Bischoff/Pässler:
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I detached the steam-pipe and the screws from the base and lifted it off. The cylinder cover is a later addition (in the older photos I posted before you can see what it looks like underneath). One oiler-cup has broken off (the one on the bearing close to the flywheel). It is still there, but the previous owner has tried to glue it to the base...
That's what you see underneath:
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