Tilt out window balance

This looks like a S795-27, with a 15-198 hook attached on top. Our standard versions of these balances have a screw-on tab instead. We can still help, but we need a little more information to determine the best course of action. 

• Can you show us the slot in the jamb track where the hook attaches to? It's shape will determine what option will work for you. 
• You said one window had balances with different stamp options (27B and 27C). This should not be; they should be the same. Can you give us the exact weight of the window sash? That will determine what stamp option you need. 
• How many balances of each stamp option do you require?

From there, we'll get this started for you. 

30 lbs would be higher than the weight range for 27C (17 through 22 lbs) or D (22 through 26 lbs). Did you ever have trouble keeping these windows open? Were they ever difficult to open? If so, then the balances would have been too weak for the sash weight. If it is indeed 30 lbs, you'd want the 27E instead, which covers 26 through 30 lbs. Just double-check this to be safe. 

The good news is, if the holes in the window jamb are square-shaped, you don't need balances with the hook attached. Instead, you can buy our standard S795-27 along with the 26-200 Screw Plug. The plug goes right into that square hole, and you can then screw the S795-27 into place.