Chainlube might work, not sure. There again when it's used on a m/c the carrier fluid evaporates because it's in the open. Being inside the gaiter it might stay too thin.
With the gaiter pulled back it might be a good lube to spray in there and leave until it's dried out. Then what you have is high performance grease that's worked it's way into the joint. I haven't been underneath working on that joint so I'm not sure if it's possible to remove and replace the gaiter easily.
Sounds like your problem joint is fixed...thats good.