The pressure gauge on my Topeak Joe Blow Ace floor pump is not working. The pump works fine. How do i take the pump apart and what should I be trying to do to repair?

Http://www.ehow.com/how_4779541_inflate-bicycle-tire-presta-valve.html

1. Rotate the wheel so the valve is resting just above the floor. Remove the valve cap.
   

2. Unscrew the locking nut on the valve stem. Quickly press down the stem to loosen the seal. You should hear air escaping when the stem is pushed in--if you do not, loosen the nut and try again.
3. Press the pump head onto the valve and flip the locking lever to make a seal. You'll hear air escape, but it should stop after you've locked the lever. If air continues to leak out, remove the pump head and reattach it.
4. Make two pump strokes and listen for air moving into the tire. If the pump handle becomes hard to press down after only a few strokes, or if the pressure gauge elevates extremely quickly, remove the pump head and repeat Step 3.
5. Inflate the tire to its recommended pressure. Remove the head by unlocking its lever and quickly pulling it off the valve stem. Secure the valve's locking nut and cap.