I have no factory ballast. The ballast is all water bladders (600lbs in the rear trunk, 300lbs on port side beside doghouse). There are usually 2 people in the boat and 1 boarder. There is no way that adding an extra 300lbs should make the transmission slip, especially a 72C which has a huge load rating.
It looks like the fluid is low. I ran the boat on the water, then checked the level and it was low. I added some on the trailer as the dipstick tube is hard to get to without burning myself on the exhaust tube. I'll check it again when I go out next. The crazy thing is that on the trailer with the engine off, the fluid level shows past full on the dipstick. I'm just afraid of overfilling.
I wonder where the fluid went to? There is no signs of leaking in the bilge area, and the transmission is clean (i.e no signs of drip stains). It's possible I guess that the fluid is leaking through the cooler and into the water supply I guess. I was pretty careful when I changed out my fluid last time to measure the same as what I took out.