Towed the boat for the first time this year, and the tranny was not acting right. I started to gte a vibration that you could feel through the steering wheel between 45-50mph. The tranny was starting to downshift on very small inclines, and it has never did this before. The tranny even started to downshift on declines, and there was a howl coming from the engine (as if the cooling fan was kicking in). I have 27K miles, so is this a sign that something is wrong or on its way out?