I purchased a Delta 12 inch disc sander from Amazon and it came yesterday. Based on advice I've read about online, I checked the runout of the wheel. I believe it is the axial runout, but you will get a better idea of it once I explain.

Basically, when I put a piece of wood against the disc near the outside edge of the disc and I spin the disc manually, I can hear and feel the disc sanding the piece of piece only at certain times. For example, I hear the disc sand the piece for maybe 1/4 of a rotation and then it doesn't sand it for 1/4 of a rotation, then it sands it again. I tried to measure runout based on the actual platter (not sure what the term is for the metal disc the sanding disc is glued to), and I got about 0.020, maybe slightly more. Is this acceptable or should I exchange this disc sander for a new one at no cost?

Also, there are slight vibrations whenever I turn on the sander. Not enough to slide the miter guide off the table like some have observed, but enough to be felt.

What do you thin I should do about these observations?