Jamie,
Look under the bed of the machine on the lip that hangs down. There should be a placard or a stamped area with a model and serial number. The model number will something like this 158-XXXXXXX. It might be three different numbers, a dash, then the rest.
Then go here {
http://www.searspartsdirect.com/part...t/user-manuals } and look for that number. There is a good chance Sears will still have .pdf copies for you to download.
As for oiling the machine, if it moves, oil it. Take off the top, could be held on by screws, or springs, open up the face plate and look for unthreaded holes. When you see 'em, oil 'em. Tilt the machine back on it's hinges and do the same. If it moves oil it.
Don't flood it, but make sure you get everything.
If the motor is oilable there will be a small hole right above where the armature shaft would fit into the bushings at the center of each end of the motor. Using a small tube put a couple three drops of oil in each hole.
Then run it.
Joe