Hi Frank,
Installing the ovision is quite straight forward, simply remove both of the old worm blocks and worm. Replace with the one piece worm block and tighten screws.
Getting a bit more into it I used an automotive feeler gauge to get the spacing right on both sides of the one piece worm block to ensure was as square as possible. Just be ultra careful when installing and follow the recommendations from ovision as to how to have your mount set up to swap the worm out. You dont want to nick or bump the new worm at all for fear of adding to the +-2 arc sec PE you could be running with after the swap
If you want pics I am happy to supply them for you
Grahame.