Soldered in a non-initialized fm24c043-g fram
ran the intialization suggested in these forums,
:DIAG:POKE 15,0,0
:DIAG:POKE 0,0,0
It remembers the rs232 configuration between power cycles, which it wasn't doing before, which I think indicates the fram replacement was successful.
It still gave 4 errors (740, 741, 747,748) at power-on for about 5-mintes, even after erasing them.
Now it has settled down to a single beep on soft or full power-on, indicating no errors.
However it still flashes the error sign in the vfd - and reports a single 741 error which is weird.
Edit. Actually the last 741 is probably due to the blank initialization.