I’m needing 6 of this style the top plastic parts are boroke and missing they are 3/8” diameter

In your photo, I am able to see a spiral balance with a nylon screw hole attachment. Did this balance ever have a plastic cover on it? If so, we would need for you to remove one of your other balances with the cover on it so that we can have you provide us with the tube diameter. Depending on the diameter of the balance tube will determine whether you would go with the Series 600 or Series 900 spiral balance as a replacement.