Hi Bob,
Have you changed fluid in the trans to a synthetic (i.e. Red Line MTL)? Have you overfilled the trans?
As others and I have found, synthetic will find ways to leak more than any other fluid. After removing the side plate covering the solenoid, no fluid should be found. If it is filled with fluid, it is most probably coming through the O-ring sealing the shaft.
In my case, I drain the cavity and clean the solenoid bore and piston. Once completed, I replaced the cover and buttoned up the trans. Presently, and for the past 2 years, I have maintained a Red Line MTL trans fluid level where it found equilibrium and stopped leaking into this cavity. Over that period, I have found the trans and overdrive work well and with no issues. I never changed the leaking O-ring, as it would require pulling the trans.
One last point, if you are using synthetic, you can always go back to non-synthetic (i.e. 30W non-detergent) and would probably not have the problem.
All the best,
Ray (64BJ8P1)