More Carb. Forensic's

Another set of carbs out the door - now operating as they should - once the pilot needles were replaced. Did the usual checks before disassembly: Float levels good, Sync good, choke and related linkages set-up well, I cleaned them again with "the Tool" just for good measure with no discoloration or debris, no carb kit but new pilot jets had been recently installed.......overall excellent work done on the refurbishing but still had an illusive "popping and farting" on two cylinders.
SOooooo - Got out the trusty microscope. Several had obvious signs of being dropped, all had been ruined with "ScotchBrite", one with severe pitting? ... not tool marks as best as I could determine and, one with a crack-like deep gouge????
At the very least, A Jewellers Loup should be in every tool box !

That's pretty bad. Looks like someone was really getting on with sand paper to make them shiny. 0r ScotchBrite like you said.
Proves again it's about precision and cleanliness to start with, then all the rest.