Help me to identify the parts needed

Your stamp is a little funny. It's telling me the balance is 26" long, but I need the sash weight to identify the new "stamp option" to choose. You say your window weighs 30 pounds. You should re-weigh.

If your window is slightly less than 30 pounds (even .1), choose 2560 as a stamp. If it weighs even a tenth of a pound over, choose 2565. If it's exactly 30, as far as you can tell, then it's essentially a matter of preference. 2565 has slightly more lift; 2560 has slightly less.

You should also check the length of the metal channel to verify that it measures 26", though.

Finally, you need to narrow down the choices for which Series you have. I can't tell if this is a Series 380 or Series 385, because the only difference is a single dimension in the bottom shoe of the balance. Measure the shoe as shown below. The 1-3/32" shoe belongs to a Series 385, but if it measures 1", it's the Series 380.