At 250hrs you either have a failed seal or a clogged vent.

There is a vent with a steel cap that allows pressure to escape all the time. The rotating oil will pressurize and gets worse as speed and load increase. If the vent is plugged it will force oil out and damage a seal or the oil burped out of the vent.

I would check fluid levels while floating level (no ballast). If low add fluid and have someone drive as you look for drips. Be careful as the shaft will be spinning and exposed. Most likely the leak is where the Trans meets the engine.

And yes red is transmission fluid