Not too sure if I am allowed to forward this but...
Spent a long time trying to locate the gasket material that goes between the glass and gauge face after refurbing my Smiths gauges, (Note: these are NOT the square sections O rings that go between the gauge and dash - they are something else.)
Finally found them at "Classic Bits" - email "sales@classic-bits.co.uk"
No affiliation to self.
Hope this helps anybody in same predicament