Brake Motor

[TrekPR]

My terminology is not going to be correct on this but I'm going to try a description and see if it is understood. Under the hood on the brake system there is a motor/pump that activates when engine power is lost and the brake is depressed. There are three screws that hold a plate to the end of this motor/pump. My seal on this plate is leaking and I would like to replace it, the question being does anyone know the part number of the seal, if the seal can be replace by itself and/or if removing the plate opens a can of worms?

[TrekPR]

Correction there are two screws holding the plate.