The modulator pressure determines the working pressures. Modulator pressure should be 41PSI with the vacuum line disconnected. I can't comment on the "other test port" pressure, not knowing where you connected. If your modulator pressure is not to spec. the transmission will slip. Don't drive that way! You can remove the modulator diagphram with the transmission installed. The adjustment screw pushes on a spring, which pushes on the diagphram, which pushes on a pin, which moves a control sleeve. Just a little bit of dirt or even lint from a rag may prevent a control sleeve from moving. They are not kidding when they say:"Don't use rags, use a chamois". A broken diagphram manifests itself by transmission fluid sucked into the intake manifold. Big time white smoke! I have seen that transmissions are advertised as "rebuilt" when all they did was to clean it. I have a drawing of the modulator assy. Best way is to fax it.
