Chain sprocket seal on a 72 interstate?

The chain sprocket seal is leaking. I have the primary off, and noticed the seal doesn't seal on the sprocket shoulder. The seal needs replacing. It appears to me, that where the sprocket matched up with the spacer, may be a source of seepage. On my old triumphs I use a small bead of sealant around the splines under the tab washer that's locks the sprocket nut in place. On the late 70's triumphs they used and o-ring, no need to seal the sprocket nut.

Are there any tricks that can help seal the chain sprocket on these Nortons?

Are you talking about the engine crankshaft seal or the gearbox mainshaft seal? Neither one seals to the sprocket.

My gearbox mainsheet seal was leaking quite a bit. I installed a new seal, followed by the spacer and scratched my head wondering
how this seal was really oil tight. After 500 miles I have only the occasional drip. I will live with it rather than tear the whole primary
apart again.

The sleeve gear machined surface seals on the bearing, bearing seals against the spacer, spacer seals against the sprocket face, all loaded by the sprocket nut..
Rubber seal-seals against a "good" /not worn grooved spacer OD. Spacers are soft and often worn and grooved. If in doubt renew since they used to be cheap.
If all is as new then it is virtually air tight.

The spacer face is not grooved, and the sprocket face seems good. I'll just install the new seal and see how it does. I have an extra seal kit, plus pulling the primary is not an issue of these bikes.

Thanks for the replies.

Replace every $uspect part.

It is not always visibly obvious but often the sleeve gear bearing is slightly loose in the worn case and will shift in the bearing bore and slide into the case a small amount yet still function. the complete assembly I described earlier will move as a set...many times a new case is required.