and then there was nothing... blown NST?

["Tesla list" <tesla-at-pupman-dot-com>]

I was putting a safety gap on my
15kv 60ma (2  15kv 30ma in parallel) transformers and i turned it on
... the safety gap sparks like crazy (obviously too small) and then ...
nothing. Well, I take the safety gap off, and I turn on the coil, all I
hear is the familiar buzzing. Well, I look around for an hour or so and I
can't find what is wrong. Well, I get a wooden stick, put a nail on it,
and ground the nail. I touch the nail to one side of the nst, sparks. I
touch it to the other side, NOTHING! this is when I panic, I turn the
coil off and touch this side. It is hot. this can't be good. I had never
looked into my nst before, and I saw foam... I have never herd of this
foam before, it is an insulator I know, but, how do you get it off to see
what is wrong? What can I do to "fix" my NST (if possible). Or,
maybe it is not my nst... anyideas?
Thanks
Adam