Toilet sound diagnosis

[Peter Brinson]

Novice here. Looking for insights. Perhaps my savvy neighbor can help or if I call the plumber, I'd like to be educated.

Listen to the rapid thumping sound coming from my toilet's back and what makes the sound almost go away:

Thank you,
Peter

 

[Terry]

Either replace the rubber washer for the toilet shutoff at the wall, or replace it.
The washer is loose and fluttering.

 

[Sponsor]

 

[Peter Brinson]

Thank you.