Well xtroll preset 30psi tank, craftsman 1hp hydroglass 40/60 pump, 40/60 pressure switch. Loss of water pressure throughout house, pump pressure gauge cutin at 75 off at 95-100. I was told to set tank bladder pressure at 35 was reading 28 prior. That changed nothing. Started to screw out nut 1 on pressur gauge but afraid off doing something bad! Please advise?

If you have a 40/60 switch, then you should be cutting in at 40 and out at 60, not 75 and 100 (which are WAAYYYY too high).

Do this: Look at the points on the switch. Are then contacting each other? If so, then is the pump running?

Have you been adjusting your control box? 00PSI will put a strain on joints and faucets. Either adjust the pressure back or replace the control.

I was told to set tank bladder pressure at 35 was reading 28 prior. The bladder tank should be charged a 2PSI UNDER the cut in point of the control box. This MUST be done with the pump shut off and the pressure bled off. Good luck, Tom