Originally Posted by Jelly
thanks for the link, looks like they only sell cylinder seal kits for some units and not helm.
Late reply, sorry.
Seastar Helm seal kit (for most single station helms) is HS5176. Includes a body gasket, a shaft seal, and several O-rings. Price is around $50 US, as far as I can tell.
You can also get just the shaft seal alone (Quad ring seal, 3/4"ID, 1"OD) for a buck or two. Seastar Seal part number is 225226.
Most (but not all) steering cylinders are now using HS5157, which includes the 2 glands, some new O-rings for the nipples and hoses, a wrench, and a, insertions guide tool. Around $100 US.
Quite a few people in the US are suggesting taking the old seals to a local hydraulic shop and having them match seals. Saves money, I suppose. I do not advocate this (for my safety), but am only putting it out there as an option.