did you check for a fuse holder as some have them. is it a variable speed graves, if so check the control circuit board for a fuse. also if it is an dc motor the brushes may be worn out and need replacing. i’m a member of the lakeside gem and mineral club of kennewick wa. and do machine repairs. there is a video on my by jarad currently rock hounding—type in mike zinski for youtube video. there is nothing wrong with useing the graves. i’ve cut on about every faceter made and have any. you can get a hold of me at gemmakermz@gmail.com