How to add a real knocker

My game has a knocker wired up in the usual spot (solenoid drive #7). I forget which game at WMS/BLY was the first to use the generic "knocker" sound, but all production MBs used it. The knocker was obviously removed due to cost. It should be fairly easy to install a knocker in any MB and have it work with either version of the software (1.00, 1.06). There is an adjustment (A.2 17) that will disable the knocker sound such that you will only hear the knocker coil if one is installed.