Really simple fix, remove the entire piece.
Start by turning off the water under the toilet.
Then there's like a plastic cap sometimes a metal cap holding that long piece that you're going to change located under that tank.
now keep a bucket handy for all the water that's going to spill all over the place.
Now that the part is off either you can go to Home Depot or Lowe's and buy one which would do the exact same job for you or go to any plumbing supply store and pick up that exact float, shouldn't cost you that much money.
You can tackle the job it's extremely easy job to do.
Not going to tell you to replace any parts except for the entire long stick.
Meaning don't be busy changing just one part, rather change the entire long stick that rod.