I saw the same Gotha engine at the weekend ( Saturday), maybe the propeller is mounted the wrong way round, ie back to front?
Also not sure why there appears to be a rusty spinner plate behind the prop.
Sadly no progress appears to have been made on the Halberstadt restoration, although two gentlemen appeared to be working on an upturned LVG fuselage whilst I was there.
Does anyone have any info as to the history of the Gotha engines?, the museum is great but there is little information on the exhibits.
Note too that there are very many wooden propellers if you look through the glass windows of the "contemporary workshop" downstairs on the ground floor, in the aviation hall.