We know the generator produces voltage, and we know the regulator maintains correct voltage, at least for a while, and without a load. What we don't know is the failure mode, whether the system slowly loses juice or quits abruptly. Having said that, tracing wires, checking crimps and cleaning grounds and contacts should be done anyway, because it's cheap and easy, before throwing any expensive parts. A new regulator won't do any good if the field wire is damaged. One thing I've learned over the years, Start with the basics. You never know, you might get lucky.