Pump won't turn on, won't stay on

I'm using a shallow well for my irrigation system.

System Particulars:
1.5 hp Flotec pump (yes, I know, but it's only use is to water the lawn)
20/40 Square-D pressure switch (The sticker inside the cover says ON: 20, so that is an assumption)
A small bladder tank, about 2-3 gallon is my guess. The tank pressure is 35.5 PSI with no system pressure.

I have good flow and water my lawn regularly, but here is the problem. The switch will not activate the pump when the pressure drops (solenoid to Zone 1 opens). I do what I shouldn't, and slide a carpenters pencil above the spring to trigger the switch, and then pull the pencil out when watering is complete (usually I remember). When watering, the pressure gauge reads 26-29 PSI, depending on the Zone that's watering. The pressure gauge usually reads about 40-42 PSI when the irrigation controller shuts off the final Zone.

As a side note, when I start to water, the pressure gauge is usually at zero. I assume that means a leak on the draw side of the pump. I do know it's something that I need to fix because if I get my primary issue corrected, the pump would then cycle as needed to maintain pressure. If I feel motivated, I may re-do the joints from the well to the pump this weekend.

I have gained lots of well information from this forum, and I thank all of the knowledgeable people that help us DIY'ers out.

Good thing I'm the curious type and was able to figure this out myself.

As I suspected, the problem was with the pressure switch. There was a pocket of silt hanging out in the diaphragm area of the switch. I assume the silt prevented proper switching operation as the diaphragm was beaten up pretty good. I replaced the switch and the system resumed normal operation. Should be good for a year or two until the silt damages this switch as well, I'll just add that to the pump re-build kit list that I buy to deal with the silt issue.

nice job but.... the tank pressure, with the system off should be 2lbs less than the cut in pressure which I believe is 20 lbs. The pump will cycle less.