My daughter has an old eletric Weedeater Model # 509 that worked well last year.  This year when she turns it on the entire head spins off.  I can't see any way to hold  the motor to tighten up the head.  Found the manual on the internet and it wasn't any help.  Me I just use roundup in a sprayer but she lives in town and wants it to look nice.  Any ideas?