I've owned 3 demons. My first one never had that problem whatsoever. The second one the shuttle valve seemed to be kind of sharp around the oring grooves, but the bolt was fine. Gave me an issue once with the thin little orings the shuttle uses. So I sold it fast, like you did, I didn't want to bother with it..
This one I currently have I purchased with completely polished internals... You'd be surprised what a difference that makes. I have the dwell 4 or 5ms lower than stock settings and it's amazing. probably one of my favorite shooting markers I've ever owned. It's as quiet as my old luxes, but gets around 9-10 pods per 4k fill.
If you're buying new, get an LV1. If you're going used, buy one of the Mayhem demons going for $300 on Nation. Hell of a steal.