By the looks of the motor (corroded) the pumps seals have gone and leaked onto the motor.
When the motor gets wet, the bearings corrode and it runs out of alignment then stopping the motor, time for a new motor.
Fit a new seal kit and piston to the pump head (not the valves) and lubricate with silicone grease.
When fitting the new motor, nip the long bolts that secure it to the mounting plate just enough so the motor spindle runs free.
If you over tighten the bolts, the spindle will not run freely and will screw the motor up after a matter of weeks.
Remove the pump head every 6 months or so to clean and lubricate the piston and offset drive bearing with silicone grease.