Hi-

I have bought a used Mazzer SJ. I replaced to new burrs and had to replace the bearings as the motor wasn't running smoothly.

After the bearing replacement I can't get a fine grind, it's very coarse at the most fine settings (I can hear burrs touching)

I'd appreciate if you have any idea how to check what's wrong / how to fix.

Many thanks!
Gadi

Considering how precise a grind has to be for espresso, it doesn't take much to mess things up. At the "finest" setting when you state that the burrs are touching, with the machine OFF and no beans or bean debris in it, see how much further the adjustment can be moved towards the fine setting. Remove one of the burrs and rotate its position one 'screw hole' and see if things improve (or worsen). Without a dial indicator to check runout on the motor or to verify that the mounts for the burrs are parallel, it will be a challenge to verify the source of the problem, if there is one. It could be that the last owner used some sort of impart force to change burrs or such and threw things out of alignment. On the other hand, maybe... just maybe, the sound you here is the burrs getting close but not actually touching, fueled by the paranoia of damaging the new burrs you just installed.