Problems like yours can result from multiport gasket failure. It's possible to replace these, but it often doesn't go well, due to the difficulty of removing old adhesive, and getting the new gasket to stick.

You'd stated earlier
Quote Originally Posted by Shifty View Post
I opened the filter and the grids looked fine with no noticeable tears or rips.
If there were -- in fact -- no failures internal to the filter, then the multiport is the next most likely failure. I don't really trust homeowner (nothing personal; just my experience here) evaluations of their filter's internal conditions, but I can't 2nd guess their judgement.

However, replacing a multiport tends to be a "go / no go" situation: you either get it replaced or you don't. So if you replaced the multiport, you'd either fix your problems or you wouldn't. If you did, great. If you didn't, then I would say, "Well the problem almost certainly is internal to the filter. You need to check it again."

As it turned out, you later stated:
Some were flexible at the top and I found a hole in the bottom of another. I am hoping if I replace the damaged grids, the problem will be fixed
but I hadn't seen that yet, when I recommended the multiport . . . even though I suspected it might be the case.

So . . . now you've seen how my mind is working, on the OTHER side of all these posts!