New alternator required me thinks

[FFMan]

Battery voltage on medium revs is only making 12.25 and voltmeter alternates between the bottom of the gauge and 12. Plus it wouldn't start after a 20min run.

I measured the voltage at the alternator too so not a fuse or wire. Dash light not on, so I guess its outputting something.

Anyhow, its a pre-serp Griff 500 - does anyone know what part I should order, from where or what its off ?

Is Halfords likely to stock or is there stuff not to be trusted ?

thanks

[FFMan]

yep - good point - I didn't check the voltage on the thin coil excitor wire. will check this out.

to be sure - which light on the dash is the charge light ?