Upon arrival customer stated that both toilets were having issues with water level in bowl receding after toilet had filled up. Inspected fill valve and flush valve on both toilets, both seem to be working properly. Inspected roof vent for clog, roof vents clear of any debris. Informed customer issue was with push button toilet and would need to be replaced to fix issue of receding water. Customer will wait before he replaces toilets since there is no damage being done.