1986 C10 intermittent starting issue

[chevymotocross]

Friend's 86 c10 305 has come up with an intermittent starting problem. He went out to start the truck the other day and nothing, no click from the starter or anything. His battery was weak prior to this so he ended up replacing battery. No luck with that.

He had starter tested at the parts store and it came up bad (I wish he came to me first since I would have saved him this expense by jumping the starter). He bought a new starter and sure enough still no start.

I checked it out. All his connections at the starter are tight, there are no burns, cuts, or corrosion. I jumped with a screwdriver from S terminal to battery terminal and it started up.

I went to the neutral safety switch and disconnected the connector there and reconnected it. Started up this time with key. I thought we had fixed the problem thinking maybe there was some corrosion or something. Later on that day he once again had a no-start issue at a gas station but was able to jump the starter with a screwdriver to get home.

Got it home, shut it off, truck restarts. So obviously it is intermittent. It is also not a heat-related issue since it wasn't starting when I checked it out and the truck was stone-cold. It wouldn't start at the gas station with the engine bay hot.

So I am narrowing this down to the NSS or ignition switch. When the truck won't start, the choke light doesn't come on and the fuel gauge didn't rise up at the gas station for him. I'm thinking because his choke light refuses to work at the no-start situations, and when his gauge didn't spike up during that time, it must not be the NSS but the ignition switch?

Here is where I got confused. While the truck WASN'T acting up and when the truck was off, I disconnected the NSS connector, the truck will still start up without that connector connected.... why is that?

Am I on the right track here? How difficult is it to replace that ignition switch? I am assuming the column has to be dropped. It is a non-tilt column.