Well, the good news is that you probably don't have to take it all apart. and you might just be able to oil it and go. Some pictures would help us to to evaluate it. Maybe a video walk around.
Do you have the whole machine, table,motor and all? Or just a head unit?
For starters, I'd oil it everywhere metal moves against metal. All the oiling points on top, everyplace underneath that a bushing, bearing or anything else moves metal on metal. Turn it over by hand and let it sit for a day. If you have the whole setup, motor and all try running it and give it a listen.
When I got my first industrial, it turned over a lot harder than any domestic i had worked with. I had no idea how tight it should have been so I erred way on the side of caution and flushed PB Blaster through everything followed by sewing machine oil. Turned it endlessly by hand trying to decide if it was too tight. I removed the internal belt so I could evaluate the top and bottom separately. After a week or so of this activity, turned out it was fine to begin with.