the tippex test is done by putting a dot on each prop in the same place and on the viscous in a line.then drive a figure of 8 full lock backwards.the dots should go out of line if the dots are in the same place then the chances are its siezed.if the freelander feels like its brakeing when on full lock backwards ie like the handbrakes half on then its probally getting tight.the original vcu,s did feel a bit tight that was normal.ie you should be able to do a full lock u turn backwards on tickover. without stalling or excessive engine drag at tickover with clutch right up.the vcu is a form of fluid clutch and allows slip so no damage is done to the ird of diff from excessive strain so both props can move at diffrant speeds.but if front wheels/prop spin faster than rear then vcu heats up and locks both props to give solid 4 wheel drive and as it cools it lets the slip come back.
hope this helps
dave