I have a late 130/5 and the headlamp vacuum switch is operated by way of a solenoid valve down at the front of the engine bay rather than the mechanical valve behind the dash found on earlier cars.
The car has been standing for a number of months and the solenoid valve has become jammed closed. As a result, when the headlamps are switched on they fail to rise, though they now do a good job of illuniating the engine bay.
Has anyone succeeded in unjamming a solenoid valve or is it time to send a little boxing day cheer the way of Paul Matty et al?
Never experienced it on my Plus2S 130/5 but 3 possible causes for the problem
A bad power supply or earth to the solenoid coil - check with multimeter and fix fault
A burnt out solenoid coil - check with multimeter and time for new valve
The valve seats are stuck together with gunk from the fuel vapors that come up the vacuum line - soak valve with a solvent such as carb cleaner to see if you can free it up.
I favour possibility 3. Ordinarily the valve can be opened by hand by pushing down against the force of the spring that holds it closed. Currently it is frozen solid.