I just cannot slow down the train, or halt it in any way. I can only put the train on the track with the power turned completely off. Once I turn the power switch on the train springs to life. If I rotate the red knob on the CAB-1 clockwise, the train will speed up to the point that it de-rails going around a bend. If I rotate it counter clockwise, it does nothing.
The Command Base must be powered up before the track so the TMCC equipment knows whether to come up in conventional or command. Let's eliminate the PM-1 as your roadblock:
Hotwire that PH-1 directly to the track w/o the PM-1 using wire stripped & folded back on itself to plug in to the two occupied sockets on the PH-1 cord - polarity doesn't matter for this test but the PM-1 passes the center socket to "A" and the outside one to "U" if you want to keep it straight for logic continuity. Connect Command Base "U" to an outside rail.
Power up the Command Base. Check with your remote that the base is receiving signals from the remote - light flashes on base.
Put the train on the track and, keeping your finger on the switch, power up the PH-1. If it takes off in conventional, it is not receiving a TMCC signal from the base... shut down PH-1 immediately to avoid crashing, and go back to your power supply and maybe switch the ground coupling to the other AC output and test again.