Are you without a switch or just got a faulty one?
Miller switches sometimes give trouble if the contacts are not pressed hard enough against the centre drum. They can be dismantled and worked on. First, knock out the roll pin and remove the knob. Then on the underside, undo the two 4BA nuts between the terminals (on the Dragonfly, one holds an extra terminal). The top and bottom halves of the body can now be separated, revealing the 2 balls and springs that locate the drum in the various positions. The drum is retained in the bottom half by a split pin - with the split pin removed, the drum can be pushed out from between the sprung fingers. Any fingers that are not making good contact can be tweaked to increase their pressure. Take the opportunity to replace the balls and springs and grease everything well with 'Vaseline'.
Initially, poor lubrication of the balls probably caused the switch to get strained as it was operated, resulting in deformation of the spring fingers and erratic contact with the drum.
Hope this is of some help,
Regards,
Eddie.
