I changed the blower motor resistor today in my 02 cavalier LSS. (Lower speeds didn't work, high was were good.
When I changed it, I dropped the blower motor by accident but seemed to spin fine and no broken fins...

But now after installing new resistor, Low speeds work great but speeds 3&4 make a loud grinding noise... I wiggled the motor & resistor but didn't do anything... do you think when I dropped the motor it messed it up??

I did put blower motor back in exactly where it came out (plug toward the back floorboard)

help please!

On the simple side I would say remove the blower again and reverify the condition and check for rubbing inside the housing.If this noise was not present prior to removing and you double check it and it continues I would just replace the blower motor.Cheap they probably are not,and imo going for a used one in the junkyard might not be much better.In short check it again removed and then decide if noisy I would go new if it were my ride.These motors can be tempermental once tinkered with and not set in just right.Idk what else to suggest as I have dealt with the issue and a new motor and resistor were both needed on a non gm ride.