Neutral Safety Switch

I'm in the middle of changing the shift shaft seals in the transmission of my 1980 D150 (318 auto). I dropped the pan and pulled the valve body to change the seal rather than attempt to change it from the top. I've also pulled the neutral safety switch.

Question: Should the neutral safety switch have an o-ring or anything to seal? It has what looks like a thin, cupped type washer but it doesn't look like it would make a great seal.

Also, should I go ahead and replace the neutral safety switch? I'm not sure if it was leaking. It had fluid on it but it may have been from the other leaks.

Thanks in advance!

That thin tin washer is the seal.. No sence changing the NSS if it was working before teardown...

Got it. Thanks for the help.