I have a heatalator fire place the rear pannel is starting to ware thin, I can see the wire mech in a 3/4" area, How can I repaire this problem?

Most panels are replaceable so the best answer is to do so. As a temporary fix, get stove cement, mix it up per the instructions and then wet the worn area. Apply a thick coat of cement over the worn area, let it sit until cured and slowly apply heat. HOWEVER, if you value your home and don't want to burn it down, do the correct thing and get a new panel.