Are you sure?? I have three of them 84 300sd, 85 300sd, and 84 300cd and they all keep pressure in the tank even for days. There is a check valve on the side of the tank but I thought that it was to keep from having a vacuum. It is aggravating at times when the pressure will bust a return line and leak for several days if the tank is half full.

Where is the little sucker and how do I fix it??

Thanks for pointing that out I thought that they were like that.
Robert