I HAVE A 50 HP MERCURY SERIAL NUMBER 5951398. IT RAN FINE AND THEN IT FAILED TO START. THERE IS NO SPARK ON ALL FOUR CYLINDERS. I CHECKED THE VOLTAGE AT THE +/- LEADS OF EACH CYLINDER WHILE CRANKING AND NO VOLTAGE IS GETTING TO ANY OF THE FOUR COILS. THERE IS VOLTAGE COMING FROM THE STATOR TO THE SWITCHBOX WHEN CRANKING BUT NO VOLTGE COMING OUT OF IT. I DID A RESISTANCE CHECK ON THE TRIGGER AND ALL SEEMED FINE. I DISCONNECTED THE KILL SWITCH WIRE AND STILL NO SPARK. I AM GUESS THAT THIS IS THE SWITCHBOX, I. MY SWITCHBOX HAS A STICKER ON IT SAYING IT IS A PN 332-5772A1 IS THERE ANY WAY TO BE SURE IT IS THE SWITCHBOX BEFORE I GO SHELLING OUT THE $$. PLEASE HELP !