A couple of weeks ago, I went to the hardware store and got the small shrader valve (the type on your car tires) typically used on top of a well water pressure tank.

Then, I drilled and tapped the back of the mast (about a foot down from the old style aluminum cast head). Next, I put some teflon tape on the valve and carefully screwed it into the mast.

Next, using only a bicyle pump set to 3-5 pounds of pressure , I pressurized the mast....went over it with a sponge full of soapy water...and VOILA, I was able to find all the leaks, mark them, and when the water evaporated, seal the leaks with 5200.

If you are to try this I have a couple of suggestions: the shrader valve comes in two sizes, pick the small one; second, Hobie put the foam mast sealer plugs (if they remembered to put them in at all) at various distances into the top and bottom of the mast, so put your valve a little lower than you might think it needs to be; I tried putting the 5200 on during a day where the air temps were in the low 70's....bad idea...it ran everywhere and took days to cure; lastly, be sure to keep your pressure low...or you will blow out already sealed areas of the mast. If you would like, I can post a picture of the what the completed valve installation looks like.

OldSalt