Oh, As far as the dust issue. Some of the smallest particles and most dangerous dust in the world is from sand. The most complaints come from the dune riders. Not near as many (not saying its unheard of) from the red dirt. Sand dust can get the high dollar paint mask with the fancy dual filters. The particles found are way smaller than any other. I here it can be hard on your lungs over time kinda like smoking.

 

Even without a filter period,let alone a leaking filter, I doubt you can ruin a motor in 650 Miles. I rode my 89 Big Bear for two years without a air filter in the air box without a issue.

 

You can and will. You got very lucky

 

I've decided what to do. Nothing.

Polaris has extended the original warranty an additional 18 months for dust-related issues. Plus I have my own 4-year extended warranty.
If the dealer doesn't want to look for the cause of this problem now, they can do it when it's far worse and it won't run anymore.