In 2011 I put a new (brand new) Wico magneto on my '48 C.

The other day, it would not start. No Spark. A simple

filing of the points got it going. It is stored in a "shelter Logic" type tent.

I wonder if it gets 5 hours running per year, I only use it to cultivate my garden.

I assume it is corrosion on the points. Is there a way to stop that corrosion, some

grease or cleaner on the point contacts during the off season?

Looked at from one angle, I got 10 years on a set of points!

From another standpoint, after just 50 hours of operation, it malfunctioned.

And last year, the float needle got stuck.

Carb.  and spark- same issues my father had with it from as far back as I can remember, like when I was 5 years old. He used to rap on the carb bowl with hammer handle. And file the points. The old tractor is bringing me back to 1963.

I would not put anything on the contacts.  They need to be clean and dry.  Just plan on rubbing a piece of brown paper bag, a dollar bill (or higher if you want), or such between them before you try starting it after it has set for an extended time.  Often the paper is all it takes to remove the oxidization from the contact surfaces.

Dielectric grease works to seal plug in connectors or sparkplug boots but the metal terminals themselves have to have metal to metal contact.  I would not put it on the contact points.