Which OEM tray are you using? I didn't see any trays made by Panny.an unfortunate incident and i feel for you.
i never had an issue with mine and am using an OEM tray with double handles..focus light is ok if it is light so it could be that yours was top heavy with a few knocks as well..i never leave my setup in a bucket with others..a quick rinse will do then lonely tub soak after last dive...i need to replace the batteries in between dives as i use high speed high area focusing for vid.
the new TZ10 is out btw with casing and manual controls though not sure abt u/w mode manual settings.
However if you really feel you want to continue with this model ZS3 and have a more solid case. go for 10G marine case..aluminum with double o ring..