repair on metal case Scantronic 9200?

Hi,i live in Newcastle and exactly 20 years ago i installed a scantronic 9200 alarm panel which i set into a wall in the hallway flush with the wallpaper! It only recently started going wrong so i got my moneys worth(seeing i nicked it from work)! Do you have a new pcb i can buy from you?When i go to bell-test -enter every light on the door just flashes and no alarms ring! I am loathe to change it as the size (dimensions) will be difficult to cover successfully with say an optima g3 or g4 which would be a logical choice? Dave 07939030440 8am-4pm (work phone) Cheers