My phone just started working again! I’m not sure if plugging it in and out of the handsfree kit a few times jiggled something or what, but I’m happy now coz it’s working… Of course, it might have been a great excuse to trade up to a new Treo 650.
I should add that Palm support did reply, but only to tell me to do what I’d already done and then possibly send it in to be looked at..
I took the opportunity to pull it apart myself, but that didn’t help, though it did clean a fair bit of dust out!