The easy way to check the volt. reg. is to do a simple +12v test using a test light or a multi meter. There are 4-5 wires, and we know the green is ground. Look for the wire going to the key switch. there should be +12v there. Use any chassis ground when doing this as you will also check the green wire for +12v. If the green shows +12 then you have a bad ground somewhere in the circuit. If you show +12 on any of the others, then your stator/reg. are working, and the trouble is elsewhere. Your next step if there is no +12v is to look at one of the zx/50 manuals as the regs. are the same as yours. You will need a meter w/ an ohm setting. Use any scale on the ohm side to check the diodes in the reg. the zx manual will show where to test. One polarity will read open, and reversing the poles should show a bridged circuit. If these tests are good then it is your stator or the wiring from it. I always buy all the parts at once, scrapping the bad bits, and keeping the good as spares. These things are ALWAYS going bad.