I have an interesting sort of problem. My old 1957 Zephyr has a very thin neck cork, which I believe was placed there by my repairman. Now, that fits my vintage Brilhart Ebolin very well, as it seems to have a very small bore (I'm referring to the part that the neck enters, not the chamber), but when I went to put another, more standard mouthpiece (a stock Selmer), it seemed to have a much larger bore (again, the part that the neck enters), and the entire mouthpiece wobbled around on the sax's neck neck, spinning and falling off freely. It was simply too large for my neck cork. The vice versa applies here as well (although I'm not sure how frequently, as I only tested one other sax), as I was unable to push my Brilhart far enough on a modern sax's neck (ie. a Selmer La Voix) to bring it into tune (the La Voix seems to have a much thicker neck cork). Now, I know with my own sax, I could always wrap the cork with tape in order to fit a larger...I guess "shank" might be the word I want here...mouthpiece, but...how do I deal with the vice versa, for instance, particularly if it isn't my own sax that I want to use that mouthpiece on? And how am I going to go about trying a whole bunch of mouthpieces at WWBW in a few weeks with such a problem? I am in desperate need of suggestions! My thanks!!