Has anyone ever tried this?

[starcraftlegasea]

I just posted recently that the power t/t on my yamaha 75 is loosing pressure slowly. After making sure that the system had the proper amount of fluid, that it had no air in it, and that the manual release valve was completely shut, the symptoms got better but did not stop completely. So what I am thinking about doing is draining the system completely and then filling it back up with fresh ATF (the manual says to do so). After that I was thinking that I would add a little ATF conditioner/stop leak additive that is supposed to recondition seals within your tranny. The stuff I got made a big difference in my truck (stopped leaks) so perhaps it will help here? Let me know what you guys think. Thanks in advance