I was right for once! Maybe your key pins are worn out, you could try spraying some electronic cleaner inside it or get a new key made.
The tumblers inside only allow the right key to be used to turn the switch and do not make any electrical contact but the switch may not be making contact within the switch itself. Those used to be cheap from the auto parts stores and are easy to change in the pre 70 cars. I used to always carry a spare but it was mainly to use on cars that I was buying and if the owner couldn't find the key, I could still start up a running car within a few minutes without digging into the wiring. I thought about crossing the terminals on the relay but many do not know about that and usually end up doing damage. If it's starting up good doing that, then it may be the switch or maybe the firewall connector is losing contact. That alone makes for a lot of problems even when these cars were fairly new.
He said he has to wiggle the key to get it to engage. So possibly the key is worn down and not pushing up all the tumblers (get a new key made) or they have dirt inside so I suggested cleaning it with electrical spray because it dries and won't damage anything. And it could be what you said but he should start off with simple stuff before he goes and changes a switch.
The tumbers that the key moves when you insert it....do not make electrical contact and getting a new key won't make any difference but if it starts when the key is wiggled, that means the switch itself is worn and it needs a new switch. The key/tumblers only allow the switch to be turned. Years ago, I took all the tumblers out of a switch just to mess with a buddy and one day I started up his car with a blank key then slid the key back out while it was still running and handed the key to him. The look on his face was priceless! It only takes a few minutes to swap out the complete switch.....
