I AM TRYING TO BUY A NEW PARTY BARGE 21 FOOT WITH A 60HP MERC BIG FOOT 4 STROKE. THERE IS A BAD VIBRATION FROM 1800 TO 2400 RPM. THE DEALER HAS CHANGED PROP & MOTOR BUT VIBRATION STILL EXISTS. TRACKER SAY IT'S THE NATURE OF BEAST. DOES ANYONE OUT THERE HAVE THIS SAME PROBLEM?