While I will probably buy a new bottle sometime this year, I decided to have a real good look at the actuation system on my current one. While not particularly serviceable, cleaning it up can give you a "warm fuzzy".
If you look at the enclosed pics, the one in the upper left shows the handle and vale assembly. The valve on mine is stainless, so that's a plus. Both handles moved very easily.
To clean the thing, you really need to take the top handle off, but that proved to be too hard. The pin is really pressed in. I thought about grinding the ends off, but I'd have to build some kind of fixture to hold the bottle and position the head to drive them out, so I resorted to a hillbiilly method to get more access.
The top handle is kept from rotating forward (why?) by the tab on the front interfering with that little square protrusion on the valve. I pinned the handles and used a screwdriver to bend the tab out so it would flip farther forward.
Before someone has a snappy comeback, yes, that weakens the handle, and no, you are't going to bend it regardless even with superman strength from being on fire.
In the upper right pic you can see the little nubbin that is pushed into the valve, into the needle, and through the burst disk. This is the problematic item, because you really can't ascertain it's condition without setting off the bottle. However, you can infer its condition.
Mine was covered with quite a bit of dirt and munge, and with some WD40, carb cleaner, and a dental pick, I got it cleaned up easily. No evidence of corrosion between the nubbin and the valve body.
Looking into the nozzle you can see the needle - it's brass, and there's no corrosion evident, so there hasn't been moisture intrusion from the top of the outlet. I put a couple of drops of WD in there and stood the bottle upside down overnight, just to give it a chance to penetrate around the nubbin. Kroil might be a better option.
When putting it back together you have to put the little hairpin clip back into its hole. When you pull the handle it pops through the hole and expands, preventing the valve from closing.
I was surprised at how much effort was required to pull the cable even without anything on the end. I pulled it out a couple of inches (do NOT let the other end disappear inside the jacket) wrapped a paper towel around the flange, and shot WD in there for a few seconds, and then did the same with the other end. It now pulls easily.
if anyone has a dead bottle out there post some pics of the valve removed and disassembled - that would provide valuable insights.