What is causing it to go out..?? Sounds like there may be other issues, and no matter what starter you put in, it may happen again. Why is yours beyond repair..?? Unless the case is damaged beyond repair, everything else can be replaced, in a rebuild. I would trust a total rebuild by a competent local shop, than buying a rebuilt "pig in a poke" online. Most of those type only replace what's needed, when tested. By that I mean, it may only need bearings, and that's all they will be replaced. If the armature is nearly worn out, but yet with some cleaning up where the brushes run will pass, they'll clean it up on a lathe, and reassemble, and send it out the door.
There are many aftermarket vendors that can sell you an OEM rebuilt starter. Take your choice. Go to Case/IH online parts store, and find the part number for your starter, then do a Google search of that part number. I'm sure you'll get a ton of hits. Check in the description, and see if they say what parts were renewed/replaced. Then shop for price.