I had a horrible, intermittent to near constant, screeching noise coming from whichever seat I wasn't sitting in when we were headed anywhere for any length of time.
I fixed it with these:
https://www.amazon.com/Super-PDR-Ali...NsaWNrPXRydWU=
She uses them as cushions to get the back of her seat just right....
They are little miracles at curing noise.
My merkur had these hand pumpers built into the seats.