

Today i recieved this brand new dremel 4250 from local shopping website but I've been struggling with tightening any of included bits. After screwing chuck in all of them stay loose like nothing has been tightened at all. Is the chuck defective? It has not worked before i surface damaged it when I struggled to remove it. Also on second picture, what i assume is extension bit for 225, does not screw fully and i don't want to force it. Should i contact the seller or am I doing something wrong? Help appreciated.