Simple job but I'm clueless...

[Jeff Handy]

Pull the cartridge again, tightly roll up a paper towel soaked in vinegar and clean out minerals and crud from inside the valve.
Squirt some clean water in there with a turkey baster afterwards, to flush out any loose crud.

Get another cartridge, goop it up all over with plumbers’ silicone valve grease on anything rubber, pull the stem forward and put some goop in there too.

Install new cartridge and cross your fingers.

If it still drips, the valve body is corroded, time to install a whole new valve.

 

[Jeff Handy]

PS Did you get a genuine Moen cartridge, or a knockoff from Danco or some other copycat?

 

[MichMich]

Yes. Got original one. Per one of the guys comment.

 

[TomFOhio]

Mich, I would try a different cartridge. If that doesn't work then you probably have a worn out faucet body. Call
Moen and they will send you a cartridge for free under their warranty.

 

[MichMich]

Guys. I've messed up. Didn't clear the pipe well enough before inserting the new cartridge... Lesson learned.

 

[Jeff Handy]

Refer back to my post # 21.

Either you left old crud in the valve body, or the lack of lube scraped off some rubber from the new valve while being inserted.

 

[MichMich]

Refer back to my post # 21.

Either you left old crud in the valve body, or the lack of lube scraped off some rubber from the new valve while being inserted.

Yeah, put lube on it. It was the old cartridge part.