Possibly not the gauge itself, I'd check the vacuum relief before replacing the gauge.
If the vacuum relief doesn't seat properly it can result in a minor but steady steam leak which can condense in the gauge. One clue is if the machine refills fairly frequently when left at idle: this can be because it is making up for the water lost to the steam leak.
If you do need to replace the gauge you only need to check the dial size, max pressure and the tube fitting. Internally they are all basically the same.