Re: B7100 Directional Control Valve / Pipe Thread question
Pardon if you already know this: The valve in front of the seat is really more a diverter valve than "directional control". It sends flow to either the 3pt lift cylinder or the (plugged) port. Flow is controlled on/off with the 3pt control lever beside the seat regardless what position the diverter valve is in. Flow only goes one way (out the port), so you need an external open center spool valve if you want to power a bi-directional cylinder or motor.
My diverter valve was stuck really solid (previous owner never used it, let the tranny fill with water). I soaked it with Liquid Wrench for a few days, gave it a few taps with a hammper then crossed my fingers and started twisting it with some pliers. It moved just the tiniest bit, but each twist loosened it up more. Now it turns freely 90 degrees. (I had the same problem with the differential lock)
If you accidentally leave or move the diverter valve to the wrong position with the port plugged then move the 3pt control lever, the pressure relieve valve will squeal, but (should) prevent damage to the pump or anything else.