I put my 1923 Conn 86I in for a complete rehab job, including replating the valves, a couple years ago. It was an expensive proposition ($1800), and I probably won't recover that cost if I ever sell it, but it was worth the expense to me; the horn looks like it just came from the factory (which was about a mile from our house). I've owned that horn since 1960; we bought it for $200 from the original owner.
D
David Bjornstad
1923 Conn New Wonder 86I, Bach 6 1/2 AL
2018 Wessex EP100 Dolce, Denis Wick 4ABL
2013 Jinbao JBEP-1111L, Denis Wick 4AM
2015 Jinbao JBBR-1240, Denis Wick clone mouthpiece of unknown designation
Cullman (AL) Community Band (Euph Section Leader)
Brass Band of Huntsville (2nd Bari)