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I always assumed one hole in the bass drum was to equalize air pressure.
Many, if not all, Wurlitzer bass drums had another hole with a fiber
bushing to pass an electric cord.  As I recall the organs in my youth,
most had an electric light bulb inside the bass drum to display the
fancy Wurlitzer decal on the drum head.  The owner often replaced the
Wurlitzer insignia with his business name, as I did with my organ when
I had one.

Dale Gunnar
Corpus Christi, Texas