[codefox1]

You are doing fine. The two on the back of the control are the on of switch. The three on the control are for volume. Disconnect either extreme end, and measure resistance end to end, should be 100,000 to maybe 500,000 ohms, but definitely not open circuit.The "arm" or center tab should vary on the ohm meter from near zero to the limit of the control as you advance or decrease the movement. Do al this stuff definitely with power off.

If you don't have a dependable meter, there are a lot of modern inexpensive digital meters (less than $25) available everywhere.