With the clarinet a feeler gauge is the best method to check as using a leak light the wood doesn't reflect. With sax you could use a feeler gauge but the most common is the leak light as there's a ton of posts and keywork in the way to use a feeler all around. A feeler gauge or leak light though probably won't do any good for pads that have multiple or stretched tonehole impressions (or porous pads). That is where ear training really comes into light of knowing the tonal quality is not what it is supposed to be. For example (I have a quick video of it) my ear led me to find weird issues such as an early Selmer Series II where they had two main keywork rib fixing pins and the body tubes had two small holes for those pins. And apparently the rib soldering did not fill in those pin holes thus the horn lacked some tonal depth which led me to explore around and inside the instrument. As soon as I found and put liquid shellac in those pinholes the horn sounded like it should have.
Do you often check sax pads (especially keys that are sprung shut) with a feeler gauge?
With the clarinet a feeler gauge is the best method to check as using a leak light the wood doesn't reflect. With sax you could use a feeler gauge but the most common is the leak light as there's a ton of posts and keywork in the way to use a feeler all around. A feeler gauge or leak light though probably won't do any good for pads that have multiple or stretched tonehole impressions (or porous pads).
That is where ear training really comes into light of knowing the tonal quality is not what it is supposed to be. For example (I have a quick video of it) my ear led me to find weird issues such as an early Selmer Series II where they had two main keywork rib fixing pins and the body tubes had two small holes for those pins. And apparently the rib soldering did not fill in those pin holes thus the horn lacked some tonal depth which led me to explore around and inside the instrument. As soon as I found and put liquid shellac in those pinholes the horn sounded like it should have.