I keep destroying my secondary regulator. Help

I haven't checked this regulator yet. I am sure the previous three were regulator failures. I don't remember brand, I have had two red and on gray, the one on it now is red. I have tried tapping on the regulators in the past, I have tried switching bottles. When I change one out it will work for a little while but not very long. This one was installed last fall. It was tested by an rv tech and showed very little pressure.