Crankshaft end float has 2 measures, with or without the primary gear installed. Without the gear installed the crankshaft float is recommended to be set at 0.020 up to .025 with a minimum of 0.010 inch. With the primary gear installed and torqued without the cork ring, the clearence is ideally 0.010-.012 and at the minimum of 0.008 inch.
When the primary gear and a new cork ring is installed and torqued, with a little difficulties the thrust washer should be possible to turn with a tool (flat screwdriver or similar).
The important sealing area is between the hardened thrust washer and main bearing surface, those must be perfectly square, flat and smooth. The cork ring is not sealing anything, but used as a spring to put pressure on the hardened washer at all times when the crankshaft is bouncing in and out.
In order to keep that gentle pressure on, the cork needs to be soft and pliable and square as well. Old cork is often too hard and can't keep up. A new cork ring should always be used so buy a couple as spares! If neccessary, mounted on the gear the cork ring can be very cautiously and carefully sanded down on a flat surface. In the worst case and pinned between a rock and a hard place, a thin gasket material can be used to shim up behind a old too thin cork ring. But buy a couple of spare cork rings!
