O.k.... here we go...
You'll have to open up the electrical component box to find out why the engine continues cranking,
Is it...
Gunk in the throttle cable casing?
Debris in the box itself?
Mis-adjusted throttle cable at the box?
Mis-adjusted GO pedal to box linkage?
etc.... etc.... etc....
heck, it could be a weak GO pedal return spring,
or maybe the GO pedal bushings are worn...
These are just some of the things you'll have to look for,
It won't be a bad micro switch, something is not returning the cable cam to it's stopped position,
and, any one of these things could be the reason it still cranks over!
You'll just have to troubleshoot it, and with some good luck, it'll be something that won't cost a thing,
and then, you'll be able to fix the other ones you have!
BTW... there is a "no cost" way to get a "pedal start" cart to idle, (mine does!)
but, if Mom and Dad are driving it also... it may not be a good idea!
Let us know what you find... I, for one, am
VERY curious!