Light knob ball & spring size?

Found what I expected: someone had been in the lightswitch before me; the upper contact must have become dis-lodged from the plastic carrier, which appears adequately repaired, but the contacts are a little out of shape. The 'loose' feel of the knob was caused by the missing ball & spring.

Manually moving the contacts, the system works flawlessly, but there is nothing holding the knob in its' position when the lights are off, the clamping force of the contacts forcing the knob to turn and the lights popping up at any given time. Very annoying, especially when the car is parked. There's also no nice positve 'end' of the rotation of the knob without the spring and ball.

So, now the hunt is on for a fitting ball & spring. Does anyone know what sizes to hunt for?

 

Hi Alan,

Hope you're well?

Yes, Verell would know, but I remembered something else: the knob, in my memorey, is the same as what I had in my Alfa Romeo Spider of 70-ies vintage, so tomorrow I'm going past an Alfa specialist locally who has some old switch-stalkx lying around. With a little luck the internals are identical and then I'll have my parts. If not, I'll ask Verell to give me some measurements!

 

Hi Bill,

Thanks for the advice, yes, I've been looking all over my garage for some, but it seems like those pesky bearing-balls disappear when you need any. Of course I could go to any bicycle shop, but then there's the matter of the spring. Too long and the knob may bind, too short and nothing's lost, just shop[ for another spring. I'd hate to be in a porition though where I can't get the knob off the switch body because that bl**dy ball is binding.

Tomorrow I'll know if the Alfa ball & spring fit.