I give up! I have now opened over 50 chests that Tinker's Goggles are supposed to have a chance to drop in. I have tried both optionals in Schemes on normal, and Bulat's chest in the Manufactury. I have pulled enough Tinker's Gloves to start my own shop. If they are not truly bugged, they have set the chance to drop so low that they might as well be. Unless the wikis are wrong about where they drop of course, but the few people I have talked to that said they have had a pair all said they got them in Schemes at the Master of the Hounds chest. None of them had gotten them in the last year though.