Bad news:In the presence of a crack, it is generally necessary toplan for replacement of the complete skimmer or parts concerned.
For what ?DIY repairs (putty/epoxy) are temporary: they don't hold up well to pressures, At freeze/thaw and to UV and the leaks often recur.
Replace immediately ifpersistent leakair intake(bubbles on return) or neck deformation.
Good reflexWhen making the change, installnew sealing gaskets, check thecanvas waterproofingaround the opening.