Thanks all for the advice and prompt responses, the o-ring that would tighten down against the bottle is in pretty rough shape, but they're all pretty dry and stiff, so I might as well replace all of them before I take it out into the field. There's a few outdoor gear stores in this town, and I've seen them online as well. I'll have to see if I can find a jet cleaning tool and drill a hole in the handle to tie it to something, I've already lost the one it came with...