Hi Lee:
Welcome to ET!!! If you do a search of these boards using "headphone jack" or similar and you will find all kinds of posts that may be of help. I have had the problem and learned the hard way. Using the headphone jack to listen to music seems to kill an internal part of the jack.
Here is one thread that may be of help:
http://www.everythingtreo.com/forum/...ht=Broken+Jack
There is a connecter made that fits over the docking connector, bypassing the headphone jack entirely. It is Seidio's Audio Out Adapter and here is a link in the ET store:
http://store.everythingtreo.com/cont...73-75--634.htm
YMMV and of course you could have a different problem. Let us know how you make out.
Good luck,
SteveTaz