Normally this problem is fuel related but run from anyone who tells you then can tell the difference by listening to the engine you HAVE to determine first if it is fuel or ignition try to eliminate spark first perhaps purchase a in line good spark tester and see if the spark changes when you...
Maybe I missed it but did you replace all the fuel lines from the tank to the carb. Ethenol will eat the line and cause flaps to form inside the line, also make sure the tank outlet fitting or valve is not blocked. If your system does NOT have a fuel pump or pulse pump you cannot use the filters...
I also doubt that is causing your issue I had one that had a groove 3 times that size the only thing it caused was a bit more oil usage. Most poor running issues are carb related, pull the plug ground it chk the spark if snapping good work on fuel delivery and carb.
I use the TRex reusable snap traps and then with the family is eliminated. I spray full strength Pine Sol all over the engine and access area's they hate the smell and stay away. The trick is to do this at least monthly to keep them discouraged....
You have nothing to lose here drain the oil put the mower onit's side and careful hit the shaft high spot with a sludge hammer until you get the shaft as straight as possible. Take your time and then put the blade back on and check your work, don't be afraid of hitting it hard, I did this with...