material inside gauge rings?

[Jim Jones <jimjcmo@yahoo.com>]

Listers:
 
I was taking my gauges apart for cleaning and repainting the trim rings and 
found this dry, brittle material inside them. The stuff that didn't fall out 
was easily removed. I assume it's some kind of packing to keep everything snug 
so the lens and trim rings don't rattle. Was this an O-ring, or something else? 
I've considered using that black 3M strip caulk as a replacement. Should I be 
looking at using something else?
 
Jim