The movable component of the start-button is nylon. While nylon is supposedly self-lubricating which is the desired property, it also easy to melt from heat. Specifically, heat from the contacts. It's wiser to attend to the contacts before a poor connection causes heat to sink the
tiny copper button into softened nylon. Once the nylon deforms the tiny copper button gets buried alive in a divot after the nylon cools and hardens around it. The movable contact is then permanently out of whack. Disclaimer: Theoretically.