OK, I picked up my M&E polymer today, and the little cork endpiece was dislodged and obstructing the embouchure - it subsequently fell out of the head. I can re-place it, but the cork is very loose, and will likely move again. Presumably it has shrunk. What keeps this in place normally - friction? cork grease? other?? How can I fix this?
TIA!
Yikes! That’s some serious shinkage! That should be a friction fit, though I’ve heard of some being affixed by the owners (not widely recommended). Let’s see what the flutemakers say…
If the cork is that loose, it will need to be replaced. If the head cork leaks at all, the tone and reponse of the whole flute will purely suck.
I’ve had good luck with corks from wine bottles…of course, it won’t work if you opened it with a corkscrew.
You need a cork at least 1/2 inch thick, an inch is better. You want to sand it or turn it until it is tight but not so tight it can’t be pushed around with a dowel in the flute.
Lube it up with cork grease before you put it in.
Proper placement general rule: the near end of the head cork should be one inner diameter of the headjoint from the center of the embochure hole.
This will usually work out to be in the neighborhood of 17 to 19 mm.
[grin] For a more metallic tone, glue a dime to the near end of the head cork. Lesl, any comments on this technique? [/grin] 
–James
You can always wrap teflon tape around it till it’s snug.
If the old cork isn’t crumbling, run a glass of very, very hot tap water, drop the cork in, and let it sit until the glass cools down. The cork may well rehydrate and be fine.
As for wine bottles, if you don’t poke all the way through the cork with that corkscrew, you can easily use a wine bottle cork - just use the side without the hole.
As for a dime on the cork, I’ve found they add value to the sound…about 10 cents worth. 
Eric
Thanks, this is very helpful!
I’m heading out momentarily to our local kitchen session, and thankfully, I have a second flute - this has got to be a good arguement for owning more than one (imagine that )
Just put it in water and it should swell up. I’ve had shrinked corks (although not to that extent) and I’ve been able to solve that issue by just letting them soak in water for a while. If it once fit fine, and has become to small due to shrinking, it should be able to swell up to normal size again.