I reassembled the chuck this morning.
Cleaned out the dried grease.
I was all set to fill it with 90w oil as directed by the Walker rep when I spied a hole in a corner.
Wanting to follow their advice and put oil in the base, I enlarged the hole to take a 10-32 set screw. I dipped the set screw in Permatex and screwed it in snug.
Filled it with a quarter inch of 90w oil, applied more Permatex to the edge of the base and popped on the mag plates.
Other than the plates being about 30 lbs and very hard to hold, it was a dead easy job.
The actuation shaft is still lousy but that's a job for another day.
I then turned my attention to cleaning the bed. I stuck a rag in the coolant outlet and liberally brushed the bed with paint thinner. Like some kind of archaeology dig, layer, upon layer of grinding grit slowly came loose. I scooped it out the muck and eventually got it grit free.
About a half dozen rags later, it's pretty clean.
On the other hand I am less clean.