Mine went Tetons up on me so I got a replacement and after Installing it I decided to take a look inside to see what is what and how it works.
It is actually quite a bit of engineering , I expected to find a simple spring solenoid....but this is Porsche.
It is a gear driven device with a small DC motor. The motor shaft has a small gear which drives a much larger gear suspended or supported by a recoil operating device very similar to a push lawn mower. Made quite well inside and a dab of grease, the recoil spring is metal (spring steel I suppose). It is a very efficient design with not great current demands considering what it accomplishes. I could post some pics if anyone is interested.