The tailgate step on my 7 seater 1999 Land Rover Discovery 2 TD5 had corroded badly under the plastic tread.  I was quite surprised how bad the corrosion was when compared to the rest of the vehicle.  Since a new step mechanism was going to cost around £200, I decided that this one should be repaired.  There are two long bolts that secure the mechanism to the chassis.  Fortunately these bolts came out without too much effort.

There should have been two layers of steel plate inside the step, but the lower one has completely rotted away.  The remains of the top one can be seen inside the plastic tread cover after it was separated from the arm.

Here is the top plate and the end of the arm that it used to be welded to.  Fortunately I can use the plate as a template for making a couple of new ones.

The arm mechanism is in general good condition with just a couple of corroded areas at each end.  This can easily be repaired.

The first job was to draw around the old plate so that I could cut a new one out of some thick steel that I had.  I also marked the positions of the slots that are used to hold the plastic tread cover on.

The photo below show the first plate cut to roughly the same shape as the original was meant to be

The photos below show the reconstructed step ready to fit on the Discovery.