It's been about 4 years since I built my gas tanks. The Andair locking gas caps worked fine then. I greased up the seals, put them on, cleaned up the tops and taped over the caps to keep paint/dust out and left it like that until last month. Last week at the airport, I attempted to open the tank caps to start gassing and calibrating the probes and the key would hardly go in either side. I soaked the key opening and filled the cylinder up with Mouse Milk for several days. That helped some and I can get the key in and wiggle it to bottom out but it won't unlock. I also used WD-40 soaking for 2 days, added heat, poked with a dental pick, blew it out under pressure and still no help. I have already put a bend in one of the keys and don't want to use any more force trying to get the cylinder to turn. The cap will turn a couple degrees then hit the stop. The cylinder will also move a degree or two. My guess is internal corrosion from electrolysis since no contaminants could enter the lock. Any suggestions before I call a locksmith out or destroy the locks??