Before I try any more tweaking, I have a question. I recently filled that subairway gap on a Feadog D with wonderful results. So I tried the same technique on my Generation F. I spent the better part of an hour trying to loosen the glue on the mouthpiece with very hot water and finally, my son, in an effort to help, gave the mouthpiece a mighty twist, and it came loose. It also cracked. I almost cried, but I went ahead and filled the gap and put the thing back together, adding a bit of a superglue to the 1/4" crack in the mouthpiece. I guess the tone is improved, but I am afraid to try tweaking another Generation. And, according to an electric tuner, that Generation remains a bit flat. No sliding up or down of the mouthpiece seems to help. If I can’t be fairly certain of removing the next mouthpiece without damaging the whistle, I’ll stop right now and live with the sound I’ve got. I know the Generations are supposed to have extra tough glue, but I’m reluctant to use water that’s too hot, lest I warp the mouthpiece. I’ve got a candy thermometer and a meat thermometer. Can anyone give me an idea what temp I need to use to loosen that pesky Generation glue?
When I unglue glued whistles (Generation, etc.), I turn on the hot water for at least 10 seconds, fill a pot, and put it on the stove for one minute. Then, I let the whistle soak for about twenty seconds. Then, it’s just a matter of twist and pull. Sometimes you can do it yourself, and sometimes, an extra set of hands is nice, used in a tug-of-war fashion.
Jerry Freeman offered some very helpful advice a while back:
http://chiffboard.mati.ca/viewtopic.php?t=35449&postdays=0&postorder=asc&start=15
The discussion was about generation C’s and Bb’s particularly, but I imagine the principles can be elaborated.
Thanks canpiper. That’s just what I was looking for. I’ll give it a try on the Generation Bb.
If I were to pick one Generation as my favorite it would be the Bb. 
I’ve got to agree with you Tommy.
I have one of those nifty instant hot water things which always works to get the Whsitle heads off. If they are super reluctant I get the grippy thing used for opening cans.
I love that Generation Bb as well, and it sounds even better with that subairway filled. My only problem with it is that I have small hands and my fingers are still not quite stretched enough to consistently reach the lowest hole when needed. I think it’s getting better though.
You know what, being new to whistles I wanted to try tweaking one (a generation D) and noticed the head was glued on. I never herd about heating them so in trying to get the head off I took a piece of ½ inch PVC pipe that was about two feet long. Stuck the bore end into the PVC pipe and slide the whistle into the PVC pipe as fast as I could. When the plastic head hit the rim of the PVC pipe it stopped but the brass body kept going. An instant unglue job with no heat at all. I have done the same to several whistles now with no problems.
I’ve found out that warm spring water is not enough to loosen the heads, but warming a cup of water in the microwave makes it possible.
Enough water to completely cover whistle head, heat for 2 mins in a microwave, submerge head for 15 secs remove head ( wear a glove it’s hot) 4 gens and 2 feadog so far without damage so it works. I found valve/cork grease applied to barrel makes a good seal.
D
What key where the Gen’s in? The water thing’s worked for me with D whistles, but have you ever tried it on a Gen C or Bb? We’re talking about a whole other world of problem. Jerry Freeman doesn’t even use the water thing for those, as he says the shaft is just too big for the fipple.
Some gens, especially the key of C, are very difficult to loosen. Immerse them in boiling water for 5 to 6seconds, then you can twist off any fipple, without damage. Well, it worked for me.
Gen C’s and F’s, and LBW’s can be problematic. On one C the fipplectomy required cutting a kerf in the back of the fipple with a Dremel disc, tweaking away, filling the kerf with epoxy putty, then lubing with anhydrous lanolin. Quite ok now.
My Gen C required a smart tap to dislodge the head (I used a steel ruler for that - I personally don’t care about the odd scratch but as it turned out there was no scratching). As Gerry and others pointed-out the C head cracks and needs filling. My Bb Gen has a mind of its own - when I first got it, the head was already loose enough for tuning purposes - right now it’s stuck tight - tomorrow it might be llose again depending on its mood.
Just to update it worked for me on Gen C, Bb, and Eb, also with Waltons D
I may be just lucky, Jerry has the wider experience so go with Jerry ,seems sensible.
D