In reply to purplemonkeyelephant:
Sikaflex 291 would probably do the job admirably. Or maybe Captain Tolley's Creeping Crack Cure if you can't get a sikaflex nozzle in? I've not used CTCCC, but I have used sikaflex for other things. It's ridiculously sticky stuff - you can't peel it off things like you can do with silicone bathroom sealant. It is also incredibly strong, if you use it to bond two items together, invariably one will break if you try to pull them apart. Be warned - it has 'breeding properties' - get a blob on your finger, wipe it off on something. You now miraculously have the same volume on your finger as you started with, plus an equal amount on whatever you wiped it on!