Went looking through the nearby boxes to see if any accessories were stored near the machine. But I found the manual!!-- in Hungarian. I used the sandman-collectables website to determine the model number, I guess it close to 15-96 anyhow.
Its doesn't seem to be 15-96, but the manual is for a 15D-88. All the info online is in German. But ISMACS says for a 15-88: C.B. Shuttle. Drop feed. "11 o’clock" bobbin case finger. Spoked wheel. Round plate; with reverse feed; feed dogs drop. Treadle or electric.
It is possible that the D in the model number signifies Germany as its country of origin? I don't see any 15D models... But at least I know the Hungarian names of the machine parts!!