Agree ^^ the switch and connector look good. You MIGHT have a short somewhere. Fusing in those circuits is very poor
Might be a failed switch, they don't cost much. You can remove the lock cylinder and keep your present keys. ANY of the circuits fed by the switch are at risk. If the switch is intermittent (broken inside) an ohmeter might not show up an obvious problem.
1....start wire. This is one wire, traditionally yellow, goes from switch, out the bulkhead, to your start relay. It's certainly possible the start relay developed an internal short
2....Coil bypass circuit, traditionally brown. This is a separate contact, also hot only in start, and feeds hot battery to the coil + for start. Unless the ignition system has a big problem, this might be down the list.
3...Switched accessory. This is hot in run or ACC and feeds batt voltage to the switched buss on the fuse panel. It's a short wire from the switch to the fuse panel, but if there's a problem in there "could be"
4....Ignition run, or IGN 1...Hot ONLY in "run," feeds several things under the dash and in the engine bay and IS NOT FUSED. Feeds the warning lights and I believe cluster gauges, etc, and goes through the bulkhead, feeds ignition, V regulator, depending on year feeds other smog doo dads, electric choke if used. This might be a likely suspect
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HOW TO TEST
You have a multimeter? With a "big" current scale like 30 amp scale? "Rig" your self a test jig from the parts store. You need some wire, say, no12 or at least 14, a 20A inline fuse holder, and your meter if possible.
And you'll need a couple -three of male "push on terminals" like the one on the right
"Rig" the wire and fuse off a battery source, such as your starter relay battery stud, the big stud on the relay.
Now, you can hook that wire and "push on" connector into the individual circuits in the switch connector and test for shorts, and if you have a meter, you can measure the current draw of them. you'll have to use your head as to what draws so much depending on what you have energized.