Fixed my leaky sink by replacing the Plummer’s putty under the strainer.
I asked the guy at Lowe’s to make sure I got the right tool to remove the large nut.
The wrench he handed me looked too small, but he said it was the right one.
I should have trusted my instincts.
After I got home I was frustrated to see that it was too small, so after some cursing I went and laser cut my own tool that fit perfectly.
(Sorry for the crappy post, uploaded with my iPhone)