I have limited experience with washer pumps but have brought several pumps off of 240's back to life. The ones I fooled with had bound up in the pump portion; the motor itself was fine. You might find that yours is a siezed pump rather than a bad motor. Good luck.

Randy

Repairing windshield washer pumps:

If the windshield washer pump doesn't work on your 240 and you have determined you have power to the unit there is a good chance that all that is wrong with it is that the pump is seized up.

Begin by removing the pump from the car. It will be necessary to plug the hose from the washer fluid reservoir or all the fluid will be lost. A pencil stub works nicely to plug the hose. Care should be taken while removing the hose as the plastic nipples can become brittle with age.

Remove the four screws on the bottom that hold the assembly together. Once you have separated the motor from the pump take the motor back to the car and reconnect the electrical lead. Turn on the ignition key and move the wiper control to the wash position. If the motor does not operate check again for 12 volts at the connector. If 12 volts is present and the motor doesn't run this fix isn't going to help you. I've tried to repair four of these and only one had a bad motor. Once you have determined that the motor is good turn your attention to the pump assembly.

You will probably find that one or both of the gears in the pump are either seized or binding on their shafts. Remove and set aside the wheel that the motor drives. *Apply pressure to the top of the shaft and push it in. A little high quality penetrating fluid might help. As you apply pressure the shaft and the attached brass gear will slide out; grasp the brass gear and pull the shaft free. (*I have been told that this is a little confusing and that all I need to say is remove the bottom plate being careful to not lose the plastic gear which may or may not be tight on the shaft)

The second gear still in place is made of plastic and can be brittle. Work carefully and try not to put pressure on one point. Apply penetrating fluid and give it a chance to work if the gear is tight. Once the gears have been removed and everything is cleaned up you may find it necessary to slightly ream out the plastic gear with an undersized drill bit (by hand!) The shaft with the brass gear might turn easier if its opening in the pump base was reamed slightly as well. I didn't find it necessary to do this but the plastic gears seem to shrink over time (much like the gear in the speedometers). I lubed the friction points with white lithium grease before reassembly.

The brass plate needs to have any build up cleaned off and be careful of the rubber gasket. I found it easiest to remove the and put it in position on the pump base before reassembling. Sealant shouldn't be necessary, but if you decide to use it apply it so that the excess squeezes to the outside rather than internally. Replace the wheel that couples with the motor; care should be taken that they engage properly as you bring the two assemblies together. Reassemble the unit using moderate pressure on the four screws. Arrive at this final moderate pressure after several series of initial crisscross patterns of snugging the screws up.

Zee, a fellow Brickboarder, had the following helpful addition:
I smear a little bit of Jack's Formula grease on all rubber gaskets used
in underwater applications. Available at most good swimming pool stores, it
is made by popular pool pump manufacturer, Hayward. It is a synthetic
petroleum jelly that keeps the rubber lubricated and supple in chemically
harsh environments. Unlike PJ, it will not deteriorate the rubber.