Before replacing anything, be sure that the bulbs have, in fact, failed.  The easiest way is probably to use a DMM to measure voltage at the bulb's contacts but reaching both sockets at the same time may not be so easy.  Competing for "easiest" is replacing one of the bulbs with a known good bulb.  Or moving a suspected bad bulb to a known good socket.

I agree with @DanielGriscom:  replacing halogen bulbs with LEDs which are physically and electrically compatible is very unlikely to be successful.