Tenant clogged sewer 3x in 3 months

[Brock Bonnicksen]

I have an issue with a tenant repetitively clogging the sewer, and requiring a plumber to unclog each time. The first two times I hired the plumber and covered the costs. The plumber believes it is an issue with use - flushing too much, or things that shouldn’t be flushed. At this point I’m unsure what to do since it’s not an issue with the actual sewer. Do I notify the tenant that they need to hire the plumber to unclog? I have attached a copy of that section of my lease agreement, which specifies MAJOR repairs are landlord responsibility and MINOR repairs are tenant responsibility. If anyone has any thoughts on how I should approach this, please provide feedback. Thanks!