Another reason to run lean, less coke!!! (and shorter barrel life, thus negating the need to worry about such matters).

And surely you could fix some arrangement up with a very short bit of tube and a repair washer to let you use the thread on the shaft to pull the shaft out? If you're doing it in situ getting a "claw hammer" into the top cylinder could be a little challenging. Then again if you're the sort of diligent owner who services RC valves in situ I doubt you've got a claw hammer in your toolbox in the first place.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread