The spring is usually not the problem. The various plastic parts that hold the contacts for the switch inside the pod housing turn to dust . These parts are unavailable.
Electrical problems are the norm for a 35 year old motorcycle. It will be worth the trouble and time to learn what's happening in those wires. Going through the harness from end to end and cleaning all the little connectors will avoid unending little problems, and you'll learn a lot! get the Honda wiring diagram and spend some time figuring it out, the various simplified wiring diagrams available will cause much confusion since they leave a lot out and will not be specific to your bike anyway.
The 12V electrical system is not dangerous, you won't get a shock from it unless you poke wires through your skin.
Unless you have amazing dexterity forget about rebuilding the stock start switch. You can do several things - bypass the headlight shutoff so the headlight works and forget electric start, bypass the headlight shutoff and connect a simple low current (2A?) SPST button for start, replace the switchpod for somewhere around $100.00, use the SPST switch plus a relay to keep the shutoff function, wire an external (these will not fit in the pod) higher current rated (I would use 10A) momentary pushbutton or toggle switch to handle both the headlight cutout and start functions.
