I found my points adjusting procedure:
The points are a simple and basic electrical switch. When closed they draw current through them, charging the coil. Open, allows the coils to spark the plugs. There are only two electrical connections. One side connects to the engine case, the other connects to the coil. Pay attention to the wire terminals on the points so they aren't allowed to contact the engine case, and be certain the insulation collar on the post is centered.
Once the connections are confirmed, rotate the crank so that the points are at their most open position. Ignore the timing marks for now. Set the mechanical gap to book spec. If you apply power now, an attached light will shine bright as the lamp filament provides an electrical path around the point contacts. Now rotate the crank until the light goes out. This is where the 1.4 F mark should align. The main plate screws are loosened just enough to allow the plate to rotate. If the main plate is undersize, the spring pressure from the points can move the main plate in the engine bosses and this can change the gap. The crank's cam position can alternate which spring is dominant as the crank is turned...which changes the gap setting you just made, because the plate can move with loosened screws. I like to shim the plate, so it can't move laterally in the engine bosses. The shims I use are feeler gauge "fingers". Now, when you rotate the plate, the 1.4 point gap doesn't change, and you can rotate the plate to a position where the light will come on as the F mark aligns with marker. Lock all three screws of the main plate down tight and do a final check of both max gap on the highest point of the cam on the crank, and that the light comes on when the marks align. You can remove the shim now. Next move on to the 2.3 point set. Again rotate the points cam to make the points open their widest and adjust the gap. Then rotate the crank for 2.3 F mark alignment. The 2.3 points have their own sub plate, which is moved on top of the main plate, to get the light to illuminate as the marks align. In most cases, you are now done with point timing. If ever you loosen the 1.4 plate screws for any reason, you will need the shim for the plate so the plate will hold lateral position, particularly if you attempt to use a dynamic timing light. I've done both, and no longer use the Dynamic to set basic timing, only to verify that the advance is working properly.
If you "run out of range" on either point set, you'll need to pick another of the three engine bosses to place the shims, and start over from the beginning with the 1.4 points. I have yet to develop a rule about which mount boss to shim. I think I used the lower left, last time I did this. Now I just insert shims where ever is the largest before loosening the three screw for the 1.4 plate, 'cause that's where it was needed last time I did the adjustment. No need to do the same work twice.
There is a FAQ entry about shimming the points plate.
The index mark on the case is used to find TDC and other references to crank position. But if your advancer rotates with slop on the crank, the mark will not indicate the correct crank position. I don't see how you will ever get accurate timing without getting that advancer located on the crank in its proper position.
I don't know the cause or what has worn between the advancer and the crank mount or if it only has worn in one direction. If yes, then it will either advance or retard your set timing actual. If it has worn in both rotational directions as I suspect, somewhere in the middle is the actual timing reference. The procedure I described earlier with JB weld can restore this accuracy and repeatability. But, you would first have to find true TDC and then install the advancer to re-calibrate it to the crank. With the present slop, it is now uncalibrated. TDC is found with a degree wheel and a piston stop. Doubt you have these. But, if you are handy, you can make instead of buy these. It involves putting on the degree wheel on the crank, and rotating the crank to piston stop inserted int the spark plug hole, noting the degree setting there. Then reverse turn the crank to the stop again. TDC is exactly half way between the previous setting and the current setting. Remove the stop and rotate the crank to that midway setting, and you have the crank at TDC, Top Dead Center. The degree wheel can be removed and your advancer plate can be placed, and you can find out then if the wear was unidirectional or if it indicates true somewhere in the middle of the slop.
Hope this can be understood.
