It helps to get a diagnosis to see exactly what you are dealing with, because we can only guess. MG only remains alive on equipment, coops, hair, clothing, and shoes for about 3 days. Once all of your present birds die off in years down the road, or if you cull, waiting a few weeks before getting new healthy baby chicks from a hatchery will ensure that you won’t have it anymore. But instead of culling I would close your flock. Since they are getting better, you may want to take some time before doing anything hasty. MG is a fairly common disease in backyard flocks and some wild birds carry it.