yeah I know. This was pretty catastrophic! I had good 40W tubes in it too (well maybe not "good" but they were full wattage lamps; GE-made DoIt lamps).
I've actually never seen DoIt lamps before. i don't know where they're sold. I guess it's a store brand? They were in one of the twin 1977 fixtures from the ReStore. The other twin fixture had red-etched 34W lamps. i kept one RS and the other one IST8 and will replace the preheater at my grandpa's shop.