The Source bearing consisted of a chunky brass housing with a screw thread which had a hardened steel thrust plate at the bottom of the bore, lined with two ptfe sleeves to take radial forces. The housing was attached to the sub-chassis with a large nut and lock washer.
The spindle was steel, hardened and ground, with a countersink machined in the end, which rested on a chrome steel 8mm ball.
If the platter is tight and not free running, then there are some simple things to try.
The sub platter should lift out. If it is stuck and doesn't move at all, then the oil in the bearing will have dried out and it would be best to initially try a solvent such as Zippo lighter fuel to try and loosen it, by tilting the deck and letting run down the bearing. Use plenty paper kitchen towel to stop the fluid getting on the deck surface. Give it 5 minutes, then see if there is any movement.
If not, then an alternative is a product such as Liquid Wrench, or other penetrating oil, which can be directed to the bearing via the little tube they provide. Leave it to work overnight, then repeat if necessary.
Once the sub platter is out, clean up the shaft with solvent and 0000 grade steel wool. Rinse it well with lighter fluid to ensure no wool or residue remain on the surface. then wipe with oil. Clean off any belt rubber residue on the rim. (While you are at it, do the same for the motor pulley, using lighter fluid, and put a tiny drop of oil on the shaft of the motor so that it runs down into the bearing.)
Remove the ball bearing from the housing by using a magnetic screwdriver or suchlike. If it is pitted, buy a replacement ball. The ball is chrome steel, 8mm.
Pour lighter fluid/ penetrating fluid, into the bearing housing and use cotton buds to clean it out and remove residue from the sleeves and thrust plate. rinse with lighter fluid and dry it out.
The bearing housing only needs enough oil to cover the ball halfway. Don't over-oil as the sub platter spindle will displace it as it enters the housing. Wipe the spindle with oil prior to inserting it. Remember to put the ball in before replacing the sub platter.
Use specific turntable oil or compressor oil to relube.
The sub platter will take some time to sit properly in the housing, because the air has to escape as the platter drops. Don't force it down, let it settle by itself.
While you're at it, replace the belt. A Thorens TD150/160 belt will do.
Note: Only use polish on the outer platter. Don't use it anywhere near the sub platter and bearing, or the motor pulley.
For reference, if the motor and PSU seem ok, then there are a few other things to go wrong, other than in the bearing. The motor pulley might be slipping on the shaft, or, as mentioned above, the belt is stretched and too slack, or there is rubber residue on the motor pulley and sub platter, causing rough running.
