For closing the case again I always cut a new paper gasket and apply a thin layer of non-hardening sealant. Works perfectly! I even wonder if a gasket is necessary at all considering the flat surfaces.

Brilliant, thank you Thomas, very much appreciated.

Hi Jason! Both surfaces on my 1937 Model 9 are flat and I am pretty sure that you situation is the same. So, you should continue with a blade. Never use a screwdriver, it would damage the surfaces so that you will not get the case tight again.
Cheers and happy Easter, Thomas

Happy easter all... I have a 1939 600 Lion (b30), I am currently doing a mechanical overhaul. The previous owner has, siliconed the little oil bath cover on with black silicon...

I have tried prising, tapping and a Stanley blade between the joint to no avail....before I go all out and try and knock a screwdriver between the joint, does anyone know if the 'mating face' is flat, or is the a seating ridge...

I obviously don't want to cause any damage, but I can't see any other option, the bearings need to be changed so it has to come off!