Happijac 4500, crank socket won't come out

New to me Bigfoot truck camper, came with 4 different Happijac electric corner jacks - 4100, 4160, 4500, 4560...so I have no idea how old any of these are, and assuming at least two of them have been replaced at some point.  

Two work...OK, one is completely dead, and one was binding horribly.  Even my big Dewalt corded gear reduction drill struggled to get that corner raised enough to get the camper on my truck with the gear clutch removed. 

Started tearing in to the binding one today for inspection, a 4500.  Got the motor assembly off, got the C-clip at the end of the bevel gear off, and can't get the socket itself to budge in/out at all.  It feels a bit snug trying to rotate it, but my little cordless drill can fully extend/retract the leg with the whole thing on the workbench without much issue, so it's not bound up.  I've been pounding on it with screwdrivers and drifts from the inside, even going as far as to drill another hole in the jack outer body to get a more direct angle on the socket shaft with zero in/out movement. 

It FEELS like I'm missing another c-clip somewhere, but I sure can't see anything.  I also noticed that it looks like the socket is a two piece design, with the shaft that drives the bevel gear moving in/out about 1/8", but the outer female hex portion not moving at all in/out.  So there's has to be something else holding this thing in?