Check this site out.
Also, if you have not done so, search "AR" in the Vinyl Forum @ audioasylum.com. There is a lot of pertinent info contained in the archives. You can ID/research the arm as well.
I recall "Merril" modifications being popular with the AR decks (might be worth researching). Think Merril was a person/company.
I've found a bit or two on AudioAsylum tonight; I'll keep looking. Yes, Merrill offered a bunch of mods to the AR tables. Like an idiot I didn't buy any of them at the time. Merrill stopped offering those mods a while ago. Well, the only excuse I have is that back then I really didn't have the money to throw around. There's a fellow listed on the Vinyl Nirvana site that seems to have taken over (in spirit) for Merrill.
I had the original AR Table many years ago and got all the full blown mods on it from George Merrill at the time.Then I thought vinyl was dead and I sold it for almost nothing,to this day I kick myself in the pants over this.
I had the new motor that would not hum,new platter acrylic,new outer ring clamp something simmiliar to VPI's that cost $500.00 by itself,new suspension ,also 1 inch cutout for the arm you specifically requested for the table.
The cutout was integrated with the subchassic,Your spindal was sent to them to get remachined to perfectly fit into the platter and would take a few hours to fully seat into your table once you got it back from George.I also rewired all the wires under the table with Kimber Silver and this opened things up even more,and I replaced the .22 600V cap with a Rel Cap and it still improved the sound.Oh well in life you win and you strike out.I'm back to a VPI MK3 Table now with no turning back Good Luck on your Quest..
Yes, I kick myself in the pants every time I think about not biting the bullet back then and sending in my ES-1 for the full Merrill mods. Easy to say that now, but back then money was an issue. It's just too bad that his company stopped doing that kind of work. Anthony Scillia seems to have taken over; he offers new armboards, adjustment studs, SS shaft, and a spring kit. But no subchassis upgrade.
76, how did you like the Merrill acrylic platter? And was the Rel Cap the same value as the original?
Fix it up. New motor, belt, arm, armboard. Either new springs or a carefull adjustment of what you have. Discard the bottom plate and either run naked replace with 1/2" baltic ply. Look into an external power supply or try with an isotap to reduce the AC to ~85watts. This reduces torque- so you have to give the platter a nudge when you turn it on, but the lower voltage also results in much smoother motor rotation (less vibration transmitted to the TT). The difference is audible.
Denon 103 cartride, Shure V-15vmr, Grado Wood bodies are a few of the favored cartridges.
Seriously for the money and very little effort, this isn't another table out within $1000 that can touch it sonically.
Good Luck !