Some time ago, I experienced a similar reduction in washer pump pressure. I had some time so I took them apart to find out if there was anything I could do to bring the pressure back up. In every case I found that (If the motor was still working) the problem was a build-up of calcium and minerals that had accumulated in the fluid-passages and the pump-gears. I ended up soaking and scrubbing all the parts - sans motor. Once the parts were re-assembled (I replaced the bottom-plate rubber seal with a bead of silicone sealant). The newly re-assembled pumps worked like new. The problem was calcium and crud build-up inside. If I were to do it again, I would clean them out a little differently. If the pump was putting out any fluid at all, BUT NOT LEAKING, I'd attach the feeder hose that runs from the washer fluid tank to a container filled with(properly mixed) CLR (Calcium-Lime-Rust) remover. I would run the solution through the pump until the pump ran clear. I would also disengage the outlet hose so no CLR would get sprayed over the window! It's also helpful to take a sewing needle and insert it into the sprayer-nozzles on the hood and give the needle a few turns to break up any calcium build up in the nozzle outlets.

All these things worked for me. My original (re-built)pumps are still working fine. Since I re-built them, I run a quart of CLR solution through each pump (I have a 245 wagon) once a year.

Good luck!