The way this works.  I have you send me your generator. If you dont have generator i most likley do.  First I test and inspect it to verify this is indeed your problem. I will probably than rebuild your generator even if it is not your problem and if it needs it, but first discussing it with you via phone.  And than just refund any funds as rebuilding your most likely will by substantially  less.  If it is bad most likley I will just send the rebuild unit.  With most older generators I  resoldered armature and turned and undercut, bearing, bushing, brushes, and lacquered fields. I set the third adjustable brush (depending on application) amperage at what I call that sweet spot so it will carry the lights but will not over charge the battery, and also have it polarized for a positive ground (again  depending on application) so all you need to do is bolt it on.  Than I run it on test bench to make sure all was good.  I have been doing generators and starters and alternators in my own shop for over fifty years and now do just vintage ones.  I have always looked at rebuilding as recycling, I try to reuse as many parts of the original as possible (most often the used parts are better than new replacement) but try to make sure its service life is as long as it was when new, but there is something about breathing life back into these old ones I enjoy. Most all of the generators I work on are as much as a hundred years old and do not look new, but I make them look pretty good. And if your are working on a show car let me know at time of sale, we can work out a deal to make it look as close to an new old stock as possible. It might take a extra hour or two of work but doable.  Most generators will need brushes and bushing changed every 30 or 40 thousand miles, if and when yours reaches that point I will take care of it for you for the price of shipping.  I will give this a life time warranty (my lifetime) no matter what the cause. I am 66 and probably have another 10 years left in me and I can’t imagine to many wearing it out in that amount of time, if so, I will repair it for free less shipping. If this fails because of a problem with the car or pickup I will cover repairing it also , if you cover shipping. And than walk you through repairs on the car. Look at my reviews of over a 1000 with all positive. I will treat you right!