I've been having problems with a thermobog, occasionally draining, hard starting, and stalling at a full stop. The majority of the time it runs good. I've taken it a part 5 times in 5 weeks and noticed tiny brass particles in the fuel bowl every time. I'm using the nitrophyl floats and I can't imagine the accelerator pump shaft could wear that much. Any suggestions?

A good filter for the filings. spray a 2 second blast of starting fluid into each idle mixture screw port (need the thin red straw to get it in there good) for the stalling & in alot of cases E10 aggravates stalling. check that the phenolic bowl ain't leaking from the 2 wells on the bottom side

First off, are you 100% certain it's brass? Rust particles looks a lot like metal. As Robert said, get a good pre carb filter (start with a clear one so you can see anything that might show up from the tank), flush everything out, carb, lines, etc. and give it a go.

*I've also seen metal particles come out of brand new fuel lines and fittings, be sure to check those as well.