1961 IH B414 - how do you remove light switch knob?

I can't figure out how the large black knob for the headlight rotary switch is supposed to come off. There is a hole that looks like it is for a hex set screw, but there is no set screw evident. What I see in there looks like a plain drift pin. But there would need to be a corresponding hole on the other side of the knob, if a drift pin was used.

How does this large black knob come off?
 
Did you manage to remove the knob from the switch? Also, can you post a picture of it? If it is a Lucas or CAV switch it may have be the type where you push a pin into the hole. This pushes against a spring loaded locating pin. In theory, you can pull the knob off the switch shaft. It it has been there a long time, it can be a tiresome process to remove the knob without breaking it…
SadFarmall
 
(quoted from post at 15:16:34 10/01/18) Did you manage to remove the knob from the switch? Also, can you post a picture of it? If it is a Lucas or CAV switch it may have be the type where you push a pin into the hole. This pushes against a spring loaded locating pin. In theory, you can pull the knob off the switch shaft. It it has been there a long time, it can be a tiresome process to remove the knob without breaking it…
SadFarmall

I'll post a pic when I get a chance. But yes, it probably is a Lucas or other british brand. The B414 was manufactured in England.

I'll try poking an allen wrench in there to see if it is spring loaded. I've never seen one that worked like that, but I've never worked on a British electrical system before. Thanks for the idea!
 
You are correct- it has a spring loaded pin. I pressed this in with a small allen wrench and wiggled it off. The rotary switch has a hex shaft with a slot that the pin engages. Weird- leave it up to the British to come up with a strange way to make a simple rotary switch and knob!

Thanks again for the info- it would have taken me a while to find that.
 
Glad it helped. Lucas was very common in Australia. The headlamp switch on our AW-7 Diesel tractor worked the same way.
SadFarmall
 

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