Thanks 1990C4S,
The electric motor runs strong, without belt. There is plenty of compression. I can feel/hear it when I turn the wheel. I try to take it apart, first the wheel. . Before going to the store to get a puller, I used hammer to knock the wheel couple times see if it can come out. It doesn't. Instead, it's turns freely. Put everything back, it run fine :lol:. I's funny and I am happy now :)

I just got a MasterForce 20gal 5cfm 150psi 67db "80% quieter" compressor from Menards.
$350 also with 11% off.
Very happy. My only complaint might be the hose hanger is too small and too low.

With the 21gal 5hp 125psi HarborFreight I had to wear ear muffs and it still rattled my teeth.

This thing probably can't be heard by neighbors with the doors open.
Plugged it in tonight and I can literally hum louder.

Is it the black one, laying horizontal, with a belt?

This one. It fills up fast, double outlets, big motor, easy plug in and adjust regulator.
Not silent but very acceptable. 67db.
The front hose hanger is completely useless.

California Air Tools and some IR models are reviewed to be quiet as well.
I didn't find any .db charts for all of the compressors.
http://forums.pelicanparts.com/uploa...1618589523.jpg

and it doesn't have a belt. Seem like the theory of quiet = belt driven can't apply to modern air compressor anymore huh
Thanks for sharing.