Hzz, nice to 'see' you over here! :-D
A possible fix is to remove the male fitting from the port and gently! spread open the crack a bit and apply a small amt of glue to the crack (be sure not to let any get inside to the threads!!) (for glue I use PVC glue because I have 3-5 cans of it on my service van, but crazy glue should also work) Then get 2 ss clamps to put on the port, tighten them down, replace the male fitting (retaped w/ teflon). This works for me most of the time, but not always.
Hayward is willing to sell you just the body of the multiport for ~ 2/3 what a whole new 'complete' unit costs (they come with no gaskets, the top plate, handle, etc so make sure that all the other components of the multi are in good shape before buying just the body {or housing, as they are also called}) The model number is on the top plate it will start "SP 710 X ##" (if the connections are 1.5") or "SP 715X##" (if 2") - if you end up ordering a replacement, make sure it is the same model (be very careful not to get one that has "R" after the "X" in the model # as those are for DE filters and the internals are 180 deg. opposite!)