The gasket and oil deflector are held in place by the wheel studs on the inside of the axle flange, and unless the gasket is severely compromised (any oil on the outside of the deflector opposite the drain hole?) then there's no need to remove the wheel studs to replace the gasket. The deflector is supposed to route oil seepage to the outside of the axle flange and brake drum. The best way to remove the wheel studs is with a ball joint press (see pic) that's way easier than driving them out with a hammer and potentially damaging something.
Check to be sure that your axle tube vent is not clogged, which will force oil out the axle seals as the axle heats up while driving.
The axle vent did have dirt build-up around it, but I'm not sure it was plugged enough to allow pressure to build inside the axle. In any case, it has now been cleaned, so it should no longer be a concern.
There is oil covering the entire axle, inside (facing the brakes) and outside facing the drum. Does this mean the oil deflector gasket is bad? I have a roll of gasket material, can I make a new gasket for the oil deflector - or is this something I need to buy (where)?
