I have a St. Croix LTB baitcaster that has separated at the seat. I warrantied the pole, but I think I can fix this. The cork area and the seat come apart as depicted in the image. There is epoxy there that seems to have given up. I haven't had luck finding local repair shops. Any advice on best way for me to mend this myself (i.e. what to do with existing epoxy, how to clean, which epoxy to use, etc.)?

Standard 15 minute 2-part epoxy.  Clean up the epoxy that is there with a scotchbrite pad by taking off the surface finish, apply new epoxy to the female sides of each joint, and push it all back together. If the seat is rock solid then I’d try to get some epoxy under the cork with a syringe  as you’re putting it together.