Hi Nicolas and Bill,
The hammer and mallet was added on 03/01/45 and was made of sheet brass (source: Georg Hoegel). This was added on either side of the tower, directly above the navigation light. If you look at this exact location on the top image I posted, you can see a dark shape. I suspect this is the hammer and mallet sheet.
Note the pipe on the deck at the foot of the tower (on the starboard side).
Cheers,
Dougie