The vacuum supply on my 1922 Duo-Art is supplied by a six-lobe
or "steamboat" pump.  It sits next to the piano in a mahogany box.
I have recovered the pneumatics, flap valves and rollers and have
a good vacuum.

I have tried to isolate the pump and the motor by using a gasket, made
of neoprene sponge, between the mountings and the box.  However, I have
been unable to stop the low frequency rumble.  Can anyone offer advice?

Steve Greatrex
Plymouth. UK.