To prepare the board for M1 decoder installation remove five components from the light board and cut traces at four spots.  This photo shows board after components are removed and traces are cut. Tip: to remove the components use two soldering irons, unsolder both ends of the components at the same time and they will lift right off.  If only one iron is available, unsolder  one side then the other going back and forth quickly until both sides are unsolder and the part can be pushed of the solder pads with the iron.

                                                                        Traces cut here.

         Remove two diodes and capacitor here.                                       Remove two diodes here.