Thanks for the tip.  On the Waltham I'm attempting to rebuild, we
found a drill bit that would fit into the tube, then used a needle
nose pliers to 'crush' the rubber -- the rubber in this case being
so old and brittle it broke into small pieces or turned to powder.

http://mtkraabel.home.comcast.net/~mtkraabel/PlayerPiano/images/Waltham_030.jpg 

I was quite satisfied with my method, but if the grandson is not
available, I'll give gasoline a try next time.

http://mtkraabel.home.comcast.net/~mtkraabel/PlayerPiano/images/Waltham_028.jpg 

Mark Kraabel