I would take it to my welding supply shop and ask them. I got a
med. sized Victor torch handle at a foundry sale and used it,
shut it off, picked it back up and burned the ---- out of my
hand. Had it rebuilt (would have been almost as cheap to just
buy a new one!) but I don’t get “tourched” anymore when I pick it
up. There are seals in the torchs, I just don’t know what sort
of seals the Smith unit has in it, but your supplier should or at
least can get the for you from Smith.
My 2 cents.