You are correct the capacitor is only used during starting the motor. I assume the motor is getting hot and shutting off. Check the discharge side, filters etc for obstructions, it appears something is causing the pressure to go a bit high.
The wiring diagram should be on the junction box cover. You can go on line and download the manual with this information. There are a lot of A.O. Smith motors out there.
How long has it been since you have the new motor installed? Did it work after the job was completed? Very possible that the starter circuit has failed, usually when it comes on and runs but overheats and stops, the starter and run circuits are both engaged and that causes it to overheat. If you can read the wiring diagram on the motor and make sure it it correctly wired, you may save it if it is a simple loose wire. Otherwise it sounds like you will have to have whoever changed it come back and do a warranty repair.
The impeller is most likely set on a tapered shaft it is not easy to get off . You may need to get a puller to get it off. You can try adding some heat to the area with a hair dryer, don't use a torch. Be gentle.
Make sure that the supplied voltage matches your motor's setup. Most well pumps can either be configured to run on 120v or 220v. If your pump is set to 220v, and you are running 110v to it, it will run slower. Check that, and repost. I'll check back, and will help in any way thet I can.
Best regards, --W/D--
Question edited for correct spelling of maker 'Noen' to 'Moen'.
'Fix' as in it is leaking? Or tighten it down because it is wobbly, or something completely different?
Well, we can have a one on one seminar by the internet. I've been a pumpman for 20 years. I can share with you my experience (household pumps, suibmersible pumps, turbine pumps, gear pumps, piston pumps, dewatering pumps, mud pumps, trash pumps, mining pumps, solids handling pump, etc....) Just take your pick. Just send in your e-mail for assistance. God bless.
It is leaking due to a defective mechanical seal. It needs to be replaced. To replace it, is to take the pumpcase off by taking off the bolts that hold it. Then, take the impeller off to take the mechanical seal behind it. Put the replacement in, and reassemble the pump. Just get in touch with us by e-mail to get more assistance.
Move the lever or turn the knob. Check the stop tap under the sink. Make sure the faucet control knob or lever is tight, There is normally a removable cover that hides the screw..