Joe try this> with the pump running, slowly close down the 2 shallow diffusers and see if the guage will read 10 or 12, you may have have to partially close the 3rd valve also and readjust the relief valve. If you cant get a reading of at least 10 psi either the guage is not correct or the end plate ( not the contact surface for the vanes)in impeller box is scoured ((motor bearings starting to go bad)due to wobble in the shaft. This causes pressue loss within the air box.Think of it like bad compression in an engine that has good rings but a bad cylinder wall.If you cant build pressure let me know and Ill send you some pics of the situation and the fix. You should be able to build 20 psi easily with that pump (but dont)Regardless you are still pumping air you would just not know how much,Hopefully its a guage issue. Ted
