How many miles has the turbo done ?, there is no seal on the turbo in the conventional sense and these do suck a certain amount of oil past on overun, not enough to notice unless quite worn though, check for play in the shaft, will have a little in/out wiggle, but shouldn't be able to detect any up down movement.
If you need a turbo overhaul I can recommend Turbocentre 01924 404112, get a step gap seal and 360 bearing done at same time.
tabetha