I think you guys nailed it. I heavily coated the inside of the box with chalk (what a mess). Then using a Qtip I gently brushed through the many layers of sanskrit to reveal more recognizable characters. About 0.1" tall and about 0.4" from the leading edge I think I "see"



"S'G'" (or maybe plain "SG" or "S" or ???). Riesch gives several possible contractors who may have produced this part. This is really a tough one. How can one tell them apart here? What's your call?

USGIcollector, how tall are the letters in your stamp?