the only places the canvas should be possibly leaking, is at the attachment points. the seams shouldn't leak once they've swollen and if by chance, they are, then regular tent seam sealer would be the choice.
of if the OP is actually having condensation issues and not true leak issues.
can't see how the stuff to dip tools in, could be used in this case.
but with a 13 year-old hybrid, there could be a variety of possibilities.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC