I found out on my recent Marshall Factory tour that the glue used on Marshall cabs/heads/combos is water based and heat activated. If you have torn the tolex on a cab, just heat the wood underneath with a hair dryer until the glue becomes active again then stick the tolex back in place. This goes for gear from about 1995 onwards. If your gear is older than that it won't work as it will be the old solvent adhesive. Heat the wood, not the tolex, as the glue is sprayed on the wood.