Firstly check if the centrifugal advance is working, remove cap and spin the rotor by hand - it should move slightly and snap back under spring pressure. if its lazy or jammed you need to O/H or lubricate the advance weights and rotor shaft
To O/H the dissy - remove from engine - remove cap and leads leave them on engine.
TO check centrifugal advanceThe bottom gear drive has a relation mark (either a conical arrow, line or even a dot) - the drive gear/dog is mounted on the shaft with a pin. The top rotor shaft is tightened to the main shaft with a screw in the center. (MAKE A DRAWING OF WHERE THE ROTOR IS POINTING WITH THE BACK MARK ALIGNED - its TDC mark)
Look closely if your reluctor (3 pointed star thingie) is part of the shaft or removeable (if removeable use 2 screwdrivers to lever it off)
You would need to remove the entire pulse generator and ignitor assy from the distributor after intricately measuring the air gap of the reluctor and pulse generator (carefully not to break them - this is a good time to solder new wires to them if they are brittle and exposed) also remove the little circlip holding the vacuum advance and remove advance diaphragm
remove the advance plate on which the ignitor/P generator was mounted on - and you will see the centrifugal advance system loaded with a couple of springs. Now depending on design - you may also have a couple of lock plates holding the bearing in the casing.
carefully remove springs remembering which goes where - and remove the centre shaft from the core, remove weights or weights assy (depending on design) and then remove the main shaft, it will come out along with a bearing. and you will see an oil seal in the end piece too.
Inspect oil seal and bearing (I just replace them anyway) and clean all the red dust etc with CRC brakekleen spray except the advance bearing plate - just wipe the surface of it clean.
The rest is simple, the weights should be lightly greased on the pivots - and a drop of oil put on the pivot posts each - the centre shaft should be nicely greased with high temp grease, and the screw tightened fully.
The assembly is reverse, place weights and springs according to your notes, the air gap should be correctly set, place the back driving gear/dog by aligning the marks - double check where the rotor is pointing - insert/hammer pin into place.
I love socket (allen) screws - and most of the times I replace all philips head screws with them (they're tough, easy to loosen/tighten in small places)
p.s. the procedure maybe slightly different if your reluctor is part of the shaft or not, but its very simple to figure out