This is taken from UK MK IV's:

How to cure sticking vanes

If the vanes are sticking, firstly you can try removing the actuator/VNT rod and giving the VNT lever a bloody good wiggle, it's not garanteed to fix the problem but it worked for me years ago! To do this you need to gain access to the turbo either from above or below, remove the 2 X 10mm nuts holding the actuator to the mount, then remove the C-Clip holding the VNT rod onto the VNT lever, and then you can slide the rod off and remove the actuator alltogether. once it's out of the way, give the VNT lever a good wiggle and then re-fit and see it it has cured the problem. if it doesn't work then you could either do a DIY refurb, you could send it away to a company to get it re-furbed, you could try using a boost valve, or you could attempt the Innotec VNT clean.

Whole link is here, its quite technical...

http://uk-mkivs.net/forums/p/394072/...5.aspx#2692605

EDIT: ha beaten to it, should have refreshed my page before posting!