Yes these are the ones everyone agrees need replacing every 15 years are so. They have different mounting techniques. Some snap in some are held with screws. You are going to have to get inside to find out.
Hello, I do have the unit open. It looks like the bottom is riveted like the tube connections but the cans don't readily come out. They seem to be connected to the mounting plates. I read somewhere about twist locks but there are multiple wires connected on the bottom side. Maybe I'm not pulling hard enough.
I believe those have the metal can shell negative leads twisted to hold them in. Just unsolder what is connected to the negative leads and use a plier to twist them back straight, after that they should be able to be removed.
I heat the tabs up, extract as much solder as possible, then flatten and straighten them with pliers.
Heat the terminals, use X-acto knife to unfold the leads wrapped around them, remove leads. You can heat the tabs as you twist and pull on the can shell, and it will come off neatly with very little damage to the phenolic insulator.
Taking a photo before you R&R is a good record of the wiring. Good luck!
Another method if you don't need to re-use the old cap is to twist the ground lug(s) in a L/R circular motion with a plier 5 to 10 times until it breaks and then the cap will free itself easily. Getting the ground lugs perfectly flat, straight and clean is not easy, especially if they were soldered before and there's allways the risk to break the phenolic insulator if you use too much force when pulling the cap out. It's better and safer to break off the lugs.