Harry Sanders said:

I have owned a Jet 1236 lathe for about 2 years and for the first time
today I tried to remove the spur center so I could install a Nova
chuck which I just purchased. The spur center refuses to budge. I have
pushed the drift rod as hard as I can, tapped it with a mallet and hit
it considerably harder than a tap with the mallet to no avail. I have
also put oil around the spur center and have the threaded index pin in
place but nothing seems to help. Any ideas?

Get a plastic bag of ice and place on the spur center, wait a few
minutes, and whack the hell out of the drift rod. Heating the hub
would help as well, but be careful not to damage the
bearings/paint/etc. This will generally give you .001-.003" more
clearance for disassembly.

FWIW,

Greg G.