The windscreen wipers on my 1992 Jaguar XJS developed a fault where it would only work on high speed.  After a little investigation, I determined that it was a fault in the wiper motor.  There are 3 brushes in the wiper motor, one is used for high speed, one for low speed and one for ground.  The low speed brush had worn down excessively.  To gain access to the motor, I removed the wiper arms by undoing the nuts that hold the wiper arm on

The little black plastic covers then lifted out to reveal two of the screws that need removing.  I had already removed the other two screws that are visible when the bonnet is lifted.

The grille was then lifted out.

There a now three hex headed screws that need removing near the windscreen and two screws near the engine that also need removing.  The water jets also need unclipping from the wiper motor carrier.

In this photo, the carrier has been lifted forward onto the engine and the electrical connector has been disconnected

I happened to have a spare windscreen wiper motor for a Jaguar XJS.  It was from an earlier model, but was identical other than the electrical connector.  I had previously replaced the brushes on the spare motor

These photos show the before and after of the brush replacement that I had previously performed on the spare motor.

The brushes and carrier refitted to the spare motor.

The motor is held in place by 3 bolts.  The arm that connects to the motor spindle also needs to be removed, by removing the single bolt that holds it in place.

The drive arm and 2 of the motor securing bolts have been removed.

This photo shows the two motors with their covers removed.  I noted the positions of the different coloured wires, then swapped them between the two motors.

The refurbished spare motor fitted to the carrier.

The carrier refitted to the car.