Okay, I think I see a pattern here.

The 4 and 3 are the weights needed to open the door. They could be in hundred-point notation (Or something fancy, like the wieght is divisible by three...).

also, no wonder the door did not open! It was basically Shur and Foo's Canoe on #3! that's only 154 pounds. That also means if we use everyone (With mass) on the wieght panels, Foo can head in and find somthing to prop the door open.

So, a command? Examine the scale, then head back to the valve. Turn the valve, and head stright.