In reply to StuPoo2:
It's an older cag, but hasn't seen that much use, it's fits me well and there's no other damage, so seems pointless to just bin it for the sake of a couple of seals.
It's a neoprene neck cone, so was never completely watertight, but snug enough that it keeps 99% of the water out.
I've just replaced my summer cag, as it had gone a funny colour and the taping was coming undone, so don't really want to spend £££ on another cag right now. Part of me is curious about trying it, anyway.