I think what has happened is, they installed 12 volt LED's and with the converter putting out as much as 13.7 volts or occasionally a bit more, that is what burned out these bulbs. You can use better bulbs rated at 10 to 24 or 30 volts and you won't likely have this problem.
http://www.m4products.com/1142-30-28...ase-1142-1076/