CD transports are not really designed to be serviceable. I think you got lucky adjusting the potentiometer. It may have been an adjustment for beam intensity but who knows? Any further attempts to make adjustments could just as easily make things worse. On the mechanical side, you can make sure that the slide that the laser rides on is smooth an clean. Check for any old hardened grease or oil. If there is no lubrication you should not have to add any as the plastic on polished metal should have low friction. If there is old lubrication, I would just use a very light machine oil, like sewing machine oil, or 3-in-1.
If it's the same CD skipping in the exact same place, it may be that the CD is the real issue. If you polish it, do not rub in circles. You want to clean perpendicular to the CD tracks, from the outside edge to inside edge. Toothpaste and water is mild enough not to scratch the surface. If the metal is delaminating inside the CD then there is nothing that can be done.