Copper crush washer on turbo feed banjo - once they've been removed once then the washer should be replaced as they don't always seal properly.
If your turbo is shagged then you'll hear it whistling and whining like a goodun before the bearings go completely.
If you need rebuild, then I can recommend ITS Turbos - I've used them few times in the past for various turbos and they've been brilliant. Turbo comes back good as new. Their contact details are on ITS Turbos
- they still haven't got a full web site up, and first time I used them was years ago!