Installed a new 25 gal.bladder tank,switch,and pressure gauge.Switch set on 30Lb. pressure kick on and off at 50lb.Air in tank at 28 lb.You have to manually kick switch on to fill tank and at 40 lb.the pressure switch goes haywire back and forth until it kicks out at 50 lb.Then when gauge falls,pump won't kick in until you manually switch lever on and sometimes you have to try over and over to get switch to kick in.we're having to switch manually every time to get pump to kick on.When pump is running you can hear air hissing in tank until it kicks off.Installed tank 3 weeks ago and worked ok until 2 days ago when lost pressure and the repeately having to use manual switch started then.When first installed wated filled normally and could not hear the hissing sound as tank filled. Tank refuses to start when pressure drops unless you start manually.Do I have bad new switch or is the air the problem? The pump is submersible 1/2 h.p. 96 ft. deep.Everything new-tank,switch,gauge,and fittings-no leaks. At wits end!If I hold contacts in with screwdriver will start ok but when kicks out at 50 lb.and pressure drops after few minutes using water in house,have to repeat procedure.