Operating Stock Car Vibrating Mat

These have never been reproduced is what I have been told by Doug Peck and Port Lines Hobbies.  People have tried a number of things.  They are mostly sandpaper types.  I have never seen them work very well.  

Your best choice will be to get another one that is in need of repair but has a good mat. 

I seem to recall that the stuff is called Fish Paper.  Looking it up on the net, it's described as a "rubberized fiber" mat used as an electric insulator.  I have seen small sections of it in some old electronic items, and this may be what we're looking for.  I haven't had time to look into it and further.   I may be wrong.  My wife tells me that often...