99 camaro conv. The window motor did the stop start thing ,so I replaced it .The shoebox said test it before putting everything back together. Now the window works but grinds going down .Perfect going up ??? The fiberglass really flexes .Another thing the bolts seem crappy. does anybody swap these out for grade 8 .It was going so good ,now im at A sit still till I get some answers?

 

After no help around here ,two days,investigation finds that the new motor was bad .I removed it and sure the grinding was internal ,in one direction. The next one will be checked in the parking lot...