Lambretta rear hub Oil Seal/leak

[operonalan]

A "small" amount of engine oil is leaking into back hub on my tv200...not enough to be noticable externally on the hub (no oil stains radiating out from hub nut) but sufficient to contaminate the brake shoes over a short period (100 miles or so ) and render brake useless.I`ve changed shoes and oil seal once but not cured problem.Do I have to take gearbox out and replace layshaft "O" ring to cure problem or is there an easier way out?? Rear hub bearing has only done 600 miles (as has whole engine since rebuild) and shows no evidence of "play" evidenced with rear wheel off floor and rocking wheel/hub sideways/up and down....your views /assistance would be appreciated

[Toddy]

A "small" amount of engine oil is leaking into back hub on my tv200...not enough to be noticable externally on the hub (no oil stains radiating out from hub nut) but sufficient to contaminate the brake shoes over a short period (100 miles or so ) and render brake useless.I`ve changed shoes and oil seal once but not cured problem.Do I have to take gearbox out and replace layshaft "O" ring to cure problem or is there an easier way out?? Rear hub bearing has only done 600 miles (as has whole engine since rebuild) and shows no evidence of "play" evidenced with rear wheel off floor and rocking wheel/hub sideways/up and down....your views /assistance would be appreciated

Think you have answered your own question there , i think you need to strip and inspect first thing though have you taken the seal retaining plates of to see if the bearing is seeping between the casing and bearing i had one that was a loose fit when the enging warmed up and lit eaked around that area may be worth a check.