[prarieschooner]

sounds like a new gasket is in order!
the first step would be to carefully remove the Pump and inspect the Mounting Surfaces on both the Pump and the Reservoir. If both are in good shape then you can make a new gasket. If you want Rubber then you could trace the Mounting and cut it out using a Razor Blade, Scissors and a Punch. Use a Punch for the smaller Holes, you could make the Punch by tapering one end of some Tubing or even Pipe. The Tapered End works as a cutting tool.