Whether a tenant has to pay for a particular repair depends on the language in the lease and the interpretation of that language. If you believe that "ALL REPAIRS" were contemplated in the lease, even repairs to the infrastructure of the home and that is what the tenant thought they were agreeing to then you can probably make them pay it. That would be unusual, however, and a court would probably want to see specific language in the lease that required the tenant to make that type of repair. If the lease is silent or ambiguous with regard to this type of repair, the landlord will have a problem. All that being said, it is nearly impossible to answer the question without seeing the specific language in the lease. Make an appointment with an local attorney who handles real estate matters and your question will likely be answered fairly quickly. Good Luck.
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Normally the landlord/lessor is responsible for the costs of repairs. However, a lease may modify this with the language used in the lease IF the lease is for term of at least one year. MCL 554.139.
If your "rent to own" contract has a term of at least one year, you may be able to assess this cost on the tenant. I suggest you consult an attorney and have him or her review the contract with you.