Home built in 1954. I am in need of the counterweight (?), the tear-drop shaped piece

Hello! That's a very old door, but I think we can still help. The first products to jump in my head were our 23-048 and 23-051. Look these over and let me know if either match up. The only difference between them is the offset, so that's what you'll want to check.

If neither will work, we'll do our best to find something else!