When I turn on my faucet the psi on my tank show 60 psi and when it drops to 40 it turns on but only gets to 55psi then it drops to 30psi before turning on then it only fills to 50psi and drops down to 20 and so on till it is about 10psi.when I turn my faucet off the gradually returns to 60 psi with a couple of cycles why is this doing it?this has just started happening this week. It put this in last winter and never had a problem so what do you think?
This sounds like there must be a major restriction between the actual pressure switch and the pressure gauge.
The key symptom is that the cut-in /cut out pressure is changing - and that's not how (what appears to be a perfectly standard Square-D pumptrol, though the picture is a bit low-resolution to be certain) pressure switches work.
With a low well output, if you had the version of the Pumptol that protects the pump from low water, it would simply shut off until it was manually reset at about 18 PSI. I have one of those, and I'm pretty sure it does not go as low as 10 PSI without shutting itself off, though its documentation is vague. It may be some fixed offset below the cut-in pressure.
Barring some fault condition I'm not familiar with, the pressure sensor of the pump switch is simply going to switch on at 40PSI (always) and off at 60 PSI (always) but that is the pressure at the switch's sensor. If there's some sort of restriction causing the pressure at the switch and the pressure at the gauge to be different with the water flowing, then behavior like you have reported becomes plausible.