Craig,
I use . what is called, a "1/4" flush mount jack".
They are sealed and do not leak air.You can find them in most music stores. I know Peavey offers them as an accessory item. You can also order them from music supply companies. Carvin has them listed in their magazine. They run about $12 at the store, about $6 if you order them.
Jude

Hi ya'll,
when I plug a cord into my jack, the signal cuts in and out. Do the jacks wear out? Is it common?

I generally use a wireless airline guitar transmitter which is about as big as your thumb and does not cause any problem, probably because there is no side pull.

any comments?

thanks
Kirk j

Yes, the jack can "wear out". It's not a common thing, but I have had to replace them in the past.
Jude