hand brake oily inside

Disco failed mot on handbrake only 15%
there's oil getting in there, put new seal on and felt last year, must be gone again, someone said check breather isn't blocked, so remove filler plug and blow through from engine bay? If it's blocked will blowing through clear it? Will the seal still need changing?
Can these seals go so regularly, just bought another one (britpart)

seals can often leak even with new genuine one ,check flange were seal contacts isnt grooved pitted and applying grease to garter spring to ensure it doesnt come off helps ,can be sign of wear in rear bearing but would expect other symptoms with that too