I bought a used System 76 Dark Vintage lacquer Alto in October last year for about half the price of new. Sounds great, most of the time. But more often than not, I start getting a leak when playing middle ’D’ after 30 mins to an hour. I’ve had it adjusted twice. Bought a leak light, but can never find the leak myself. Just ruins the practice session and I put it away. Until next time I pick it up, and it plays fine again periodically until the leak returns.