I have a pair of Charmoz boots which are a few years old, but still in good condition and more than adequate for my needs.
I've got a gash between the midsole and the rubber rand. It starts just after the toe bail, and runs back about maybe 4cm with a depth of about 3mm.
The sole is still solidly attached with no increased flex.
Is there a good way to fix this, or am I looking at a resole?