Well.. No matter what, it is best to replace the switch. Then you could cut it open and get the answer, as plastic parts can wear and or break at anytime. It is a replace and toss item.
If you can do without it, till its replaced, just take it out and tape both ends of the wire, make note of witch one went on top, but really isnt a big deal for the DC switch..
If the switch is needed, just jam a toothpic in when turned off or on or tape on or off, so it wont move itself and create a partial contact, or unwanted contact.
It also might be what i found below, and would be best to check it if it heated up.
I did just change a toggle switch for a old camping lady about a month ago. It lost all its switch on and off resistance, it was easy to feel it. I took it out and the rear was overheated, as it had a boatload of older type DC bulbs on it that sucked lots of power when all were on for long times. It took a wile but overheated. I took the feed hot wire off and tapped it up till new switch came in. Easy cheep fix/replacement.
The best place is the next place.