VECTOR: SW rubber stoppers for yoke

I am looking for a suitable replacement for the rubber bumper/stoppers that  
are used when the yoke is maxed out in either direction.  I was installing  
some of my repro overlays recently (shameless plug!) and these things are all  
melted and gooey.  Yes, the games are stored in a hot warehouse.  I  can't even 
find one good enough to see what it is supposed to look like.   anybody have 
a good replacement?
 
 
Thanks
 
Dave