You might be able to fix that by soaking it in CLR for an hour or so (longer if you can). It likely dislodged some lime or calcium scale when the plunger opened the vent when the pressure went off that normally holds it shut.
The Watts unit looks like a good choice if you must replace it. May have different nut size or thread pitch so sweating it in may be required.
The Watts unit looks like a good choice if you must replace it. May have different nut size or thread pitch so sweating it in may be required.