Art,

My decision to keep draining and refilling was based on knowing there was still alot of old fluid in there. I turn wrenches on aircraft for a living (mostly helicopters)and I am familar with hydraulic system contamination. The internal passages in an automotive transmission are not nearly as small as our helicopter hydraulic boost systems. I figured if I could get enough clean fluid in there, the detergent properties may disolve whatever crud is trapped and fix the problem.
Draining the pan only gets about 5 or 6 quarts of fluid. The remaining 6 0r 7 quarts are still in the converter and various passages, clutch packs,ect. Facing the prospect of having to pull the transmission, I figured it was worth the effort to continue my procedure at home and see what happened. I agree that if the former owner had serviced the transmission sooner, I probably would not have experienced the problem. The other variable is I really don't know how hard the car was driven before I bought it. Generally, most younger guys would drive a corvette fairly hard (I know I did when I was alot younger). Even though the transmission shifted perfectly before I serviced it, there could have been clutch material lodged in passages from hard use by the former owner. My experience is probably an exception. I just wanted to relay the story to document the fact that it can happen under certain circumstances.