Inner workings of turn signals?

[62lwbc10]

Hello all, I just noticed by 1958 shop manual dos not inlude any information regarding how the turn signals work, diagram of the system, etc. I have to assume this is the case because turn signals were options back then? Anyway, my truck has original signals and they work fine, they just dont work unless you manually hold the turnsignal lever. Im sure the little spring devices in the signal cup have something to do with this. ANyway, I wanted to work on this and there doesnt seem to be anything in the shop manual. anyone have any references? thanks, Mark