Peel and recover. Aside from that, peel back non stuck covering and spray K2R (the dry cleaning/talc in a spray can) on balsa. Remove talc dust. Do again in order to suck out fuel residue. Do again. Balsarite works better than anything else I've found. Not 100%. I've hopes for my new ARF Vector. After ironing down the covering, carefully, I have sealed and sealed again and sealed again all the covering edges with trim seal. One fellow I met at Brodak who had a spotless prissy looking ARF said his secret was to scotch bright all the covering intersections and seal them with dope, 4 times. Another fellow, after heat sealing, sprays his new ARF with two part urethane clear. He says the covering definitely does not lift. Got to hand it to the new poisonous paints with a nuclear half-life.