Firstly (with game off and unplugged) check the connectors which go into your new power supply. If they are yellowed (burnt) they could be making a poor connection, vibrations of the machine causing it to loose power to the CPU.
Next, do a visual inspection of ALL coils in the game. With my finger I usually just gently pull on the diode to make sure its not cracked or in one piece. Also check it with a multimeter and check each coil ohm.
Finally - check the fuse clips. On Data East games (nearly always) they need to be replaced.
