Just a note of warning, if you try to use an 1156 bulb - which has a single contact on the bottom - in a socket for a bulb with two contacts on the bottom, it could end really badly. Before putting any bulb in, LOOK into the socket and see if it has two contacts on the bottom or one, and match the bulb to it. As long as you match the number of contacts in the socket, you might blow the bulb, or it may not work if the bulb is wrong, but your vac will be safe. Make CERTAIN. If you put an 1156 in a two-pin socket for a 12v light bulb, if could short out the windings in the motor.
Of course, I don't know which bulb you need. It's always best to look before you leap. Would be nice if it was an 1156, though. Because those can be had by the dozen, from ebay, amazon, or any car parts store, for very little money.