That correct wrench made the all difference getting the plugs loose. A conventional box end wrench didn't work as it started rounding the corners.
I suspect the special valve adjustment tool is special sized for the TX. I ordered one of the standard valve adjustment sets, and all the sizes were wrong-too small. I wound up using conventional wrenches and holding my mouth just so, but it's difficult to gauge the torque on the lock nut that way (at least for me).