I recently obtained one of the early Concert Roller Organs which have
the reservoir on the bottom (recognizable by the single large flat
board underneath).  This particular model had the relief valve in
the very center of the bottom board, unlike the ones with which I'm
familiar.  But it is now gone.  Which brings me to a couple of easy
questions:

1)  Does anyone else have an early model with this type of external
relief valve?

2)  If so, can you describe it so that I may reconstruct one
appropriately?

Thank you,
Todd Augsburger - Roller Organs
http://www.rollerorgans.com/