Sirui tripod parts

Does anyone have a source for Sirui tripod parts? Searches I've done, including Sirui's website, are only coming up with accessories. Specifically, I'm looking for a center column for a W-1204 Waterproof tripod. The tripod I have has a short (about 4") column - pictures I see show a longer column, and that's what I'm looking for. I don't need the extra height, I just want to be able to make adjustments to the height without adjusting the legs. My searches come up with an accessory extension column, that's not what I need.

Also, somewhere in my travels the hook on the bottom of the column has disappeared, I have no idea how or where. If nothing else I'd like to replace it. I have to think parts are available for repairs, but I can't seem to find them.