Okay, thanks for the amplification. I already tried disconnecting the vacuum lines to the 3/2 valves. That resulted in the transmission shifting like there was no vacuum at all; more of a jolt than a clunk. But I will try that again. Maybe I had a leak but I don't think so. I will vacuum test the system before driving next time. I suppose the next step is to adjust the modulator pressure, which I initially set with a gauge.