Transmission Issue Please Help

I found water in the fluid of the pcm40 1:23-1 trans in my 91. The problem traced back to a faulty cooler. The transmission fluid was a light gray and it had a low viscosity, the transmission will engage immediately in reverse but it slips when trying to engage in forward. I managed to ease the speed up to 28 but the rpm was sitting on about 3200 so it is slipping a good bit. I have tried to flush as much of the watery fluid out. Please let me know of any suggestions. Thank you in advance for any assistance.

Thanks for the info. I have manage through using an Amsoil transmission flush to get the fluid back to the “red” color after it has been idling for about 20 min. I am also fixing a hole on the silent rider replacing the bilge pump and the blower hose as they are all still factory parts on a 3400 hour boat. Adjusting the throttle and shift cable now and then a water test after I finish that (hopefully tonight). Just pull my girls 125 max weight slalom and barefoot so I hope it will get okay for that until school starts. No tubes or large hairy mammals such as myself until it has been throughly ran with the smaller skiers in my home. Thanks for the info.