By checking battery voltage while the engine is running and the lights are on.
yes
If the 71 is a standard then yes it will fit.
your generator isn't charging. try replacing the brushes. if not then try thesamba.com and look for another generator.
It depends. Generally, the answer is yes, as long it is bug to bug, or other like models. It is not true of the bus, as it changed engine formats right about then.
if it is out of a super beetle you could have some problems. if not though, it should fit
Check this site, it should answer your question about the value of a 1971 VW. http://www.nadaguides.com/Classic-Cars/1971/Volkswagen
Get the Bug Me DVD on electrics. ***OR*** visit: http://www.1302super.com/page19a.html for an official VW wiring diagram (Super Beetle only)
http://www.thesamba.com/vw/archives/info/wiring/bug_71.jpg and http://www.thesamba.com/vw/archives/info/wiring/bug_7071_key.jpg
The chassis number is written on the tunnel under the rear seat. The engine number is written on the crankcase under the generator. Then check these numbers against the VW list (theres one in John Muirs book). You probably also have an import plate that's behind the spare wheel.
I can't imagine why you would need a diagram, there are only about four wires in the VW bug engine compartment, coil, and generator.(if it's not a bug I am not sure)
how do i get into a trunk o f a vw bug 1972
In that case you have to pull the wheel and then the brake drum to access the mechanism directly.