So I suspect it's the pump. Search revealed that causes could be low fluid, bad pump, bad hoses, or low on fluid. I'll admit I didn't check it for fluid this last time I drove it, but very recently I had, and it was full. I doubt it leaked or vented, everything is clean. (or as clean as it was when I put it together lol) The hoses are fairly new, they could be checked I guess. I know the belt isn't slipping. Low speed, assist is pretty weak and intermittent, pump groans, more effort to turn the wheel. I'm pretty sure a new pump is the answer, but any experts on these things that can answer why the groaning, and is it something you can fix with a rebuild kit or something? Would be fun to tear it apart, see the inner workings of yet another component on the truck. Any sources for rebuild kits? I wouldn't be surprised if the cost/effort is such that I might as well just buy a rebuilt one instead? Maybe exchange my old one as a core in pieces just to check out the innards.