Oil leak from "main gallery access port" in New Holland 1725

[ericm979]

It looks like its a slightly oversize cylinder thats driven into the bore. I have seen that in a few engines. Sometimes its a ball and the case is peened over to lock it in. You could make your own plug and seal it with a small amount of good case sealant like Dirko or Yamabond #4. One concern is that if its too long it may block a cross drilled gallery. The step may be there to prevent driving it too deep.

I'd be paranoid after a fix like that and try to rig up an oil pressure idiot light or gauge and watch it like a hawk.