I'm replacing a near 30 year old Hayward SP2610X15 pool pump with the same model. I had to chisel the old pump base off of the studs to remove it. The owner's manual calls for fixing the pump assembly to the concrete pad. I understand that in some locales, a floating pump is allowed, although I wonder about vibration affecting PVC connected directly or indirectly to the pump.

The existing exposed studs are seriously corroded with some nut and/or washer material rusted on. A few threads might be salvageable with some die work, but replacement of the studs seems desirable. Due to the morass of existing close-in plumbing, some of which is fixed to the pump house walls, moving the pump axially or radially is not feasible without a major re-plumbing exercise that I'm a bit loath to perform.

So I ask: What method do those of you who have to deal with this suggest for stud replacement or repair? I can imagine using my hammer drill to remove a significant irregular area to get the stud out. I can imagine drilling a pilot hole in the stud and using a diamond hole saw for a neater hole, but I didn't install the pump and don't know how far down into the 5.5-inch slab the existing stud reaches. Drilling out the stud from the center would require a bit that can cut steel as well as tolerate cutting concrete. I'm not sure what might exist for that purpose. Cutting the existing stud flush and tapping it for a smaller diameter thread might work, given the low stress that should be present.

So I would appreciate some advice. I'm sure that those of you who do pool repair must have a "most-labor-efficient" solution for this.

Thanks in advance.