Water pressure gauge doesn't seem to be working

I've noticed that the water pressure gauge on my well pump stays at a constant 39 psi. I used to see if cycle as the water pressure decreased/increased. I've noticed that the pressure control still clicks on/off periodically, but the pressure gauge never changes. Is my gauge bad? It's about 4 years old.

 

It sounds like it. The tube going to it could be pluged with something. Try removing the gauge and tube and be sure the passage ways are clear. I doubt it will work but might be worth a try.