I have a few F40's left over from last year that I took them out of the pack to do some sub assembly expecting to fly them within a week or two, but then I crashed my rocket. Now the propellant has a 'skin' that doesnt burn. If I cut it away the underlaying propellant is ok, but you have to cut a fair bit off. So...can I do anything with these motors? Are they now totally dead or what?