First of all, replace the pressure gauge, it is obviously not working.
I don't really understand how this 2 pump system works---how exactly does the power get to the individual pumps, which pump does the switch control? Who adjusted the switch? Did they make sure that the pump was capable of the increased pressure? What is the kick on and kick off differential? Did the gauge work when the "adjustment" was made? Was the air in the pressure tank adjusted? Have you actually checked the pressure? There is a difference between pressure problems and volume problems. Are there any kinds of filters on the system? Explain the distribution panel ??? in the garage.
That's all I can think of now.