The weedwacking was not harassment.
If there is lead poisoning, report that the doctor and get the health department to do an inspection once the doctor diagnoses your child and makes the report. Submit pictures of the lead based paint chips once they have been analyzed and tested.
As regards the lawn mower, in writing demand the mower be fixed per terms of the lease so you may comply with the lease terms of mowing the lawn. State in the letter the lease provision that requires the landlord to provide a working lawn mower as his obligation.