The directions for removing the "turntable" (I'll call it the platter) in the service manual say to remove the 45 adaptor by turning it counter clockwise and lifting it up, then lift off the mat and remove the platter. It cautions that the platter is "tight fitted" on the spindle.
The subject of lubricating the bearing on an SL-10 has come up in the forum, and user Shoji wrote "Is also possible no problem for lubrication as most time I have seen plenty example and all is still good condition with lubrication remaining. If require to add 1 or 2 drop of oil by spindle exit from housing is good to make use of SWFO 010 from Panasonic as sell in small tube with applicator." What I don't know is whether the SL-5 bearing is the same or of similar design.
Here's a thread in which lensmanMK2 cleaned and lubed the bearing on his SL-7: viewtopic.php?f=18&t=57914
Anecdotally, I've never lubed the bearing on my SL-7 and it still performs flawlessly.
re: lubricating the rail, there have been a few posts about it in the forum. I personally used Tri-Flow to both clean and lube the rail when I got my SL-7 (about 6 years ago) and it worked like a charm. No problems.