Hi,  This is my first time on here.  I'm looking for a bit of advice on the unit I have.  Its been here for about 25 years  It was repaired by someone about 15 years ago who added a few modern looking parts.  It worked automatic with light switch for a few years and then stopped, so we just started it with push button and locking fuel solenoid in place, an d without charging.
So I decided to have a look at it to see if I could repair it.  I noticed that the big charge resistor in the generator box had a brake, so I just twisted the wires together and the autostart from light switch worked.  I've ordered some enamelled resistance wire so I can repair it properly
So my question is, Why would a broken charge resistor cause the auto start not to work?

I've included a few picks of my boxes.  I was wondering if anyone could tell me the purpose of the devices that were replaced in top box, and how to tidy them up a bit?  Two are diodes, and the other seems to be two resisters joined together.

Thanks,

Damien.