Hi Dave,
All the electrics on the Dragonfly were made by Miller. The headlight/ignition switch is a 6 position 2 layer switch that controls the ignition, lights, and charge rate from the alternator - these are now becoming quite scarce, but occasionally crop up at autojumbles. Some ingenious owners have managed to utilise the single layer version that Velocette used - but this has to be wired up in conjunction with a couple of 6 volt relays in order to control the battery charging. Unfortunately, it is not possible to substitute a Lucas PRS8 switch as used by BSA and Triumph as the Lucas alternator that goes with it is wired differently internally.
Are you without a switch, or is yours just faulty? The most common problems are poor contact between the centre drum and the terminals, or the switch seizing up so that the knob cannot be turned. Both these problems can be rectified by carefully dismantling the switch. The black body of the switch is in 2 halves and held together by the 4BA nuts on the underside. With these removed, carefully prise the 2 halves apart (careful, there are 2 springs and balls inside). With the halves parted, you will find a circlip or split pin retaining the centre drum (depending on whether it is an early or late type), the drum can now be pushed out of the bottom of the switch. The terminal blades can now be tweaked to make better contact with the drum. On reassembly, it pays to replace the 2 balls and springs, and load them well with Vaseline to prevent the ingress of water (the reason for it seizing up).
Hope some of this helps,
Regards,
Eddie.
