Bought a new primary gasket and it's rubber. Never used one of these before do I still need to dress the gasket with some sealant or grease. The primary cover is a bit battered in a couple of places where some gorilla has used a screwdriver.
I've found JB weld to be very effective at levelling out irregularities in joint surfaces. Make sire the areas are absolutely oil free before use.
You need all new Cork gaskets and a smear of silicon gasket. Works for me.
Must admit that I have a couple of Nortons. They have a rubber band intended to seal the primary. It rarely does. Best practise seems to glue one side with silicone and grease the other side. Makes it possible to remove the flimsy sheet metal outer cover without buckling it. Though I've never had problems with BSAs.
I hate silicone sealant I always end up getting more on myself than the joint. I have got blue hylomar and welseal I will try with the blue snot first and see how it goes. I think I will order another gasket just in case.
I bought a couple of the rubber type primary gaskets. Fixed to the outer cover with silicone and a bit of heavy grease on the other side as I would with a cork gasket. First impression is that it works OK but other issues like stripped threads etc mean I haven't got the primary oil tight yet so I can't be 100% sure.