U-Joint wont purge grease - should I replace it or keep dealing with it?

I wouldn’t change it till it has some play in it. I think getting grease through only half is pretty common. Doesn’t mean others are necessarily dry. You probably know, though from taking it apart before, if half of it’s not getting grease. Just want to change it right away if it gets sloppy. If not, you risk egg holing the yokes. Usually the one welded onto the driveshaft. I replaced all mine a few years back. Driveshaft Yoke was wallered out for a good 5 yrs prior. I must have changed that U joint 2-3 times, over about 4 yrs. before finally fixing everything properly. It was all original, had about 2 mil. miles at the time. I still haven’t had the new 750lb nut put on the tailshaft yoke. Hoping it would take some slop out of the tailshaft. Rear Short shaft has never been out. U joins still original, over 2 mil. Seems they never wear out.

 

Before I did all that cap and greasing work I would buy an inferred heat gun. Just hit those caps once in a while.