For an Operator's Manual, get a copy of South Bend Lathe's immortal book: "How to Run a Lathe". It is generic to South Bend lathes off all shapes and sizes, ranging from the 9" to the 16". Copies and reprints are on ebay.
If the lathe is otherwise intact and everything works, nothing broken, nothing missing, you are probably Ok without a parts manual. From your photo, the lathe is likely to have split cast iron headstock bearings. South Bend used to bore the headstock casting with the bearing caps in place on some shim packs. This was the actual bearing the headstock journals rode in. The cast iron is divided into "pads" by oil grooving. I do not think the lathes with the split cast iron bearings used felts and springs to lube the bearings, relying solely on the lubricators on the tops of the bearing caps. I could be wrong, but I did once check bearing clearances and readjust them on a South Bend 13" lathe with the split cast iron bearings.
My 2 cents: put the lathe into service, and see how it cuts. Take a piece of round steel bar, chuck it, and with a few inches projecting from the chuck, take a facing cut and a turning cut on it. If the bar tries to "climb the toolbit", bearings may be a little loose. If you get a good surface finish, chances are the bearing adjustment is fine. If you have doubts about the bearing clearances in the headstock, it can be checked with a dial indicator and a bar or piece of hardwood:
-remove the chuck from the lathe and back off the thrust bearing adjustment nut (at the small end of the spindle, may be a semi-split nut locked with a screw).
-slack the belt to the headstock pulley
-mount a dial indicator on the toolpost or on the headstock itself, so the contact tip touched the spindle on the collar or unthreaded "register" portion at 12:00.
-put some preload on the indicator and zero it.
-place a bar or a piece of hardwood about 12"-16" long in the bore of the headstock spindle. I use a hammer handle.
-press down with about 100 lbs of force, and you may see the dial indicator move in a negative direction. this is squeezing the oil out of the bearing, and should be under 0,001" movement.
-re zero the indicator and pull up on the hammer handle or bar with about 100 lbs of force. Read the indicator while holding the bar or hammer handle.
-note the reading. This the clearance in the bearing.
-I do not have Southbend specs for that size lathe, but for a heavy 10" lathe, somewhere between 0.0006"-0.001" is what I recall. On a 16" lathe with cast iron bearings, a little over 0.001" (0.0015" ?) would be OK, IMO.
-Repeat the exercise for the small end bearing on the spindle. Clearance on that bearing might be on the order of 0.0008"-0.0012" (WAG)
-The bearing caps are put down on shim packs, which may be laminated shim stock, or may be loose brass shims. Either way, if the clearance seems a bit loose based on how the lathe cuts a bar stuck out of the chuck, and based on your dial indicator readings, you may have to adjust the clearance in the headstock bearings by taking out a little bit of shimming. Laminated shims peel off. Loose shims are individual shims, and are cut from shim stock. If you lift the bearing caps, mark which side faces which way on each cap, unless there are dowel pins to establish that. When you lift the caps, bump them loose with a piece of brass and a hammer, or a dead blow hammer. Try not to drive screwdrivers or wedges between the caps and the headstock body. You will likely see that Southbend's people hand scraped the mating surfaces where the caps seat on the headstock. Make sure not to raise any burrs.
-Mike each shim, and take care not to mix up the shims from one side of the bearing to the other. Put the shims in envelopes or bags and write down what the shims were to be sure (example: front headstock bearing, operator's side: 0.005", 0.003", 0.001". 0.001")
-Make shim changes slowly, one bearing at a time. A trick that admittedly does not sound entirely right is to remove a 0.001" from one side of the bearing only. This gives a very small closing of the clearance.
-When you have the clearance re-adjusted, pull the cap bolts down and try to turn the spindle with your hands on the headstock pulley. It should turn freely.
-If the spindle turns freely, recheck the clearance with the dial indicator.
-If the spindle turns freely, my own "quick and dirty" check is to put some oil in the bearing and try spinning the spindle over by hand. If it jerks to a stop, the odds are good the bearing is set up a little on the tight side and will likely run hot. If it glides to a stop when you stop turning it, chances are the bearing is set OK.
-Repeat for the other bearing.
-When you have good clearance readings and the bearings seem OK by the hand-turning test, adjust the thrust bearing. Run the nut in until the spindle locks, then back it off until the spindle just turns freely. Kind of like doing front whee bearings on older cars.
-When you have the thrust bearing adjusted, put plenty of oil in the spindle bearings and start the lathe under power in the slowest spindle speed with the back gears out (pin in bull gear connecting bull gear to the spindle, back gears not engaged). Let the lathe run and keep feeling the bearings with the back of your hand. The back of your hand is more sensitive to temperature changes than your fingertips, think of a parent feeling a child's forehead for fever. If the bearing gets hot in a hurry, flood it with oil and stop the lathe and back off the cap bolts. You may need to add a 0.001" shim on one side of the cap.
-If the bearings get nicely warm, kind of like body temperature or a little more, and take their time getting there, then the clearances are OK.
-When the temperatures in the bearings stabilize, move the belt to the next faster step on the cone pulley and repeat the heat run. Work up to the fastest speed. If the lathe's headstock bearings are a little warmer than body temperature when the temperature stabilizes, they are OK. If you cannot keep your hand on the bearings, they are way too hot.
Unscientific, but this is the way people have adjusted and checked the bearings in plain bearing machinery and engines for ages. Plan on using high speed steel toolbits with the lathe, as it is designed for them. The older lathes were a bit slow for carbide cutting tools, and with some wear on the sliding surfaces, may not be rigid enough to run carbide tools. High speed steel toolbits can be ground on a common bench grinder, freehand, and ground to suit whatever job is at hand. The angles are not critical as long as the basic geometry is right, and with some oil stoning, a HSS toolbit on an old lathe like yours will produce a surface finish like a precision grinder.
South Bend's book will tell you a lot about using this type of lathe and about toolbits, cutting speeds, and lots more. I bought my first copy as a kid back in 1958. Kind of a timeless little text, and a good one.
