Thanks for the post byrdman4u,

Just to confirm, the unit will run but it won't build any pressure? Or, will the unit simply not turn on at all?

If the unit will not turn on at all, check the motor brushes first to see if they're worn down to nothing. Then, test the power cord with a multimeter. If that checks out, then check the copper contacts inside the on/off pressure switch, which is what the motor cord and power cord wire to. Are the copper contacts burnt or damaged? If so, the pressure switch needs to be replaced.

If the unit runs but doesn't build pressure, this is caused by either defective flapper valves in the pump head, or a worn compression ring (and cylinder cup). You would need to remove the head and inspect these components to confirm.

- MTR

Since the unit won't turn on at all, check the motor brushes first to see if they're worn down to nothing. You should be able to see them once you remove the plastic shroud covering the motor/pump. Are the carbon brushes touching the copper commutator on the armature? If so, test the power cord with a multimeter to make sure you're getting current through it. If that checks out, then check the copper contacts inside the on/off pressure switch, which is what the motor cord and power cord wire to. Are the copper contacts burnt or damaged? If so, the pressure switch needs to be replaced. Hope this helps you out!

- MTR

I was going to mention the fuse/circuit but somehow missed it in my replies. Sometimes it's the most obvious thing! Glad you found the problem.

- MTR