My neighbor has this entry lock on her front door. She is 87 years old and I help whenever I can. Her inside door handle is very loose and I have never attempted a repair on this type of door entry set. Is there any information on how to tighten up the inside handle? It has a thumb latch on the outside and a brass handle on the inside. To lock the door you just lift the thumb latch on the outside. Don't want to mess with it unless I have an idea what is inside. The inside handle is an obvious set screw but what holds the square rod for lack of a better word into the mortise? Do I ha to completely disassemble lock to repair?