My Panasonic DMC-TZ5 will no longer focus,

If you mention "ticking clock" sounds, then most probably something like a grain of sand fell into the cogs in the zoom mechanism (been taking pictures on a beach? ;). Dirt gets into the mechanism through the gaps between the zoom barrels and the camera body. One tiny grain of sand is enough to cause the lens mechanism to jam or malfunction.
Unfortunately, this is a problem with pretty much all compact zoom cameras. Usually there is not much you can do with this. First thing I try in cases like these is gently tapping the camera to shift whatever might be blocking the mechanism. If unsuccessul, then only way I know to fix this is completely stripping the lens to clean it or swapping the lens with one taken from another camera ("donors" available on ebay ;).
If you are not keen on tinkering with your camera I would suggest selling it on ebay - TZ5 with lens mechanism issues still fetch pretty good prices.

From repairman's point of view I can say that TZ5 / TZ3 (same lens design) are much better in in terms of "resisting dirt" than various other manufacturers. They are very well made and relatively easy to dismantle and fix. This is most probably the reason why even broken ones still sell quite well on ebay.

Of course, you might get unlucky with most robust piece of kit :(

Well, hope this helps.
Good luck with your TZ5.
Raf