There could be anywhere from 2 to 6 depending on the model of the mower.
you probably have a bad bearing
how do you adjust the mower deck of a john deer lt 150
I have a Craftsman DYS 4500 and there is a nut under the left rear fender next to the tire that adjusts level. I'm still having trouble getting the deck tuned again despite my best effort with a bubble level, but that nut is definitely adjusted it.
youtube - push mower oil change.... oil plug under mower deck
Use a torpedo level on your blades.
There are too many possible answers to that question since there are many many Craftsman mowers. Please ask again with the mower model number.
The drive belt is a Craftsman #140294 The deck belts are Craftman #'s 180808 & 174368
maybe your deck is too low
One can look in the owners manual of the Craftsman mower to learn how to replace the spindle bearings. Another way the spindle bearings can be replaced is to take it to a lawnmower professional.