My 51 200 has had a problem with the headlights going off at night after about 20 minutes running. The usual suspect is the circuit breaker on the headlight switch. I thought that the breaker was built into the switch and would require a NOS switch. Found out that the breaker is a replaceable part, and can be easily swapped out. Disconnect the battery, then remove the dash unit so that you can reach the switch. The knob comes off when you remove a 1/16" allen set screw, and twist off the knob. The face plate comes off with a special Packard tool, or with a pair of miniature pliers inserted into the recesses on the plate. Once the knob and plate have been removed, the switch can be pulled back, and you can reach it thru the dash panel. A 30 amp circuit breaker, Belkampf 7823105 from Napa fits in nicely. The breaker says it is a 12 volt, but a circuit breaker doesn't really care about volts, only amps. I installed it so that the wire to the lights via the dash panel is on the "Bat" side, since the car is a positive ground. A fairly easy job; took all of about 10 minutes. I'll try it out later when it gets dark to make sure all is well.
I took the car out for an hour drive, with the lights on, both high and low beam, and so far, all is well. Not often you can fix a problem for less than $4 and ten minutes of labor.
