Generator lights question

[txtriathlete]

When I start my M1009 both gen lights come on and stay on. Voltmeter is low yellow or red. I can race the engine a bit and both lights will go out and voltmeter will go to high green. If I don't race the engine and just drive it, eventually one of the lights (Gen 1?) will go out and the voltmeter will kick up to high yellow/low green.
Truck is still 24v. I tried tightening the belts but it didn't make any difference. Grounds? Both alts are charging normal when lights are off, both batteries are good and fully charged as they should be.

 

[Barrman]

It reads like your voltage regulators are going If your belts are tight and everything else is good. Buy a pair of alternator rebuild kits is my suggestion.

 

[txtriathlete]

Bummer. Was hoping it was something easy like chasing a bad ground (ha!). Thanks.

 

[Barrman]

Sorry, “Check your grounds” is kind of implied in every military truck and especially CUCV conversation. Pay real good attention to the ground cluster above the parking brake mount.