78 caprice windshieldsprayer question

I have a question. I have an 78 Caprice Coupe and for some reason the windshieldspray motor aint working. Windshield wipers work great but when i press the winshieldwiper switch to spray, nothing happends. I hear the relay ticking but the motor aint moving.

I checked if the lines were blocked, They werent. I checked the little piston and i can move it tough i need to apply a lot of force to move it. Is this normal? Should i remove the motor, take it apart clean it, grease it etc or should i just throw it away and but a different one?

And another small question. I installed a new heater core and apperently when reinstalling the blower mototr i blew a fuse somewhere. Im not getting any electric current on the purple wires anymore. I checked all the fuses under the dash but they were fine. Anyone got an electrical scheme or can point me in the direction of this fuse?

Thanks in advance for all your help!

Greets, Lesley from the Netherlands