to have a spring and as an Electrolux it will be a coil spring like in a wind up wall clock. They aren't particularity complicated, but you do have to adhere to some general principles when restoring a recoil unit. After I've cleaned and lubed up everything, including the posts...I pull the cord all the way out and make sure I have at least a couple of coils in reserve. If you don't, you risk having the whole coil jump/release and you have no tension....i.e., you start over again.

The general design of the recoil is as old as the G and basically the same into the Diamond J....maybe there were changes to it after that....I dunno. 

Kevin