Stator problem or not on 86 wing?

86 Goldwing Aspencade. 86,000 miles

Bike seemed weak to start so I bought a new battery this spring. Running fine for a few weeks on new battery but leaving work yesterday seemed a little weak restarting at work (not too bad though). Drove 30 miles. Restarted after fifteen minutes but seemed a little weaker. Drove 3 miles to get gas, then could barely turn over at gas station. Got a jump and came home. Hooked up battery charger and started fine this morning (so I don't believe the new battery is an issue).

Revved engine to 3000 rpm with multi meter and the voltage went from 11.8 to 12.5 when revved.

So, am I looking at a stator problem or something else? I've read 13.0 should be my voltage when engine is revving.

Thoughts?
And if it is the stator, at this point, 26 years old, even though the bike looks like it is only five years old (I've maintained it well, repainted it, and all new decals) is it worth the time and money to rebuild?

I'm second owner but I bought at 5000 miles in 1990 and I doubt stator has ever been replaced.