Diff nose seal

Stuck a borrowed Mk2 Sprite axle onto the car.  Everything works fine with
the exception of the seal.  Leaks like crazy.  Done the "jack it up in the
air  -  tighten the brake drums on  -  Give it some grief with a long bar."
No joy.

Any wise suggestions?  I'd hate to have to pull the whole lot off again.
Undo the check-straps?  Knock out the axle-to-spring bolts to get a windygun
on it?