Having gone through the labour intensive task of removing the IRD and gearbox to change the front diff on my Freelander (due to a siezed VCU). I was wondering whether the VCU can be reconditioned.

I have read a number of threads regarding failed VCU's but I am surprised no-one offers a reconditioning service. Am I correct in assuming that the cause of the problem is the thickening of the silicone oil within the unit.

See this link for a good insight to the workings of a VCU

Viscous coupling unit - Wikipedia, the free encyclopedia

Is it not simply the case of drilling a drain hole, replacing the fluid and sealing back up again. Can anyone enlighten me further as to why this simple operation is not offered.

have a read of this thread - and then this one.