Most engraved base 300B tubes have 4 "dots" around eveything, and
"---300B---" in the middle, but I have seen a few (mostly in photos)
that are missing a dash, like " 300B---", and sometimes a dot or two.
Does anyone know what's going on here? Maybe WE used this as a dating
scheme? I might have thought one was just from a broken stamp, but I saw
another in an eBay photo, so that's unlikely. The stamping is perfect
everywhere except for the missing parts, so it can't be that the stamp
only contacted the base on one side. It looks like either WE had a plan,
or the stamp was broken. Thanks, Phil