Roger M,
Maybe it doesn't need to charge any more. If it's charged the battery after you have run it down a little by starting the tractor, and you aren't running any accessories that need electrical power, it won't need to charge any more. You don't want it to over-charge. What happens when you operate the electric lift a few times? Does it start to charge again? (I assume you're going by the gage) If so, it sounds like the voltage regulator is doing what it's supposed to do. If not, maybe some more info would help us give better answers.
Maybe it doesn't need to charge any more. If it's charged the battery after you have run it down a little by starting the tractor, and you aren't running any accessories that need electrical power, it won't need to charge any more. You don't want it to over-charge. What happens when you operate the electric lift a few times? Does it start to charge again? (I assume you're going by the gage) If so, it sounds like the voltage regulator is doing what it's supposed to do. If not, maybe some more info would help us give better answers.