You can give them a much better chance at a long and happy life if you disable the flapper inside the airbox, and glue it down so the hot air intake is blocked.

Other than premature death by roasting, they are little enigmas. Most people simply carry a known good spare rather than preventively replace them, as new/rebuilt ones are expensive. I've scored a few recently-rebuilt units (Injection Labs sticker on them) from the junkyard for $25 each.

John