You are quite welcome. Always willing to help if I can.
The Rev/Nor switch does sound like a phase switch. These are normally used if, when sitting at your listening position, it seems that the bass just isn’t working. Most times that means the bass waves from the sub are out of phase with the main speakers, creating some sort of null at that point. If you change the switch it puts the sub up to 180 degrees out of phase, and you should notice a difference, one way or another.