dadp47
Sir, you can do the closing via string, but adjustment will drive you crazy. Either use a light rubber band or a very light spring. You can also use a light spring to open the doors. Use slightly more tension on the closing spring thant the opening spring. Go to Sears aor any good hardware store for a good selection. DO NOT only rely on the gear to open the doors or sometime, the gear will hang up on the doors, either opening or closing.
Twinman