Oil leak, Clutch end of Crankshaft

After an engine rebuild to my LR90 a leak developed from the crankshaft oilseal into the clutch housing. The seal was replaced and no damage could be detected on the seal lip or crankshaft surface. A 1000 mile later the same problem seems to have appeared as engine oil leaks from the drain between clutch and flywheel housings. Can anyone advise on the correct proceedure for fitting the seal, the manual suggests fitting the seal guide to the crankshaft, then fitting the flywheel housing before pulling the guide off.