Hello Ken & Doc,
The leaks and sticking reeds are what I term "Cox misery"! When they are leak free and have a good reed, then the Cox reedies are a joy to use. It is the dratted leaks that got me down about a year ago. I almost gave up on the little critters. Now I do a rebuild session and replace all the known nasties at one fell swoop, usually about 10 engines at a time! I also use some silicone sealent on the screws as per Doc's recommendations. Once, when I ran out of o-rings, I used the old ones with a touch of silicone. Not to be recommended, but it does work if you are stuck for parts, provided you use the barest minimum.
Since I have started to maintain my fleet on a regular basis, the "Cox misery" has gone away and I am very happy with the results of regular and careful rebuilds. So is my grandson, who is the main user of the fleet!