To get inchworm...
1. Shoot the ferris wheel so that the ferris wheel light goes out.
2. With the ferris wheel light out, and after the dummy stops talking (or is it), and no quick score lit, shoot the ferris wheel again. You should get the "shoot ducks to light ferris wheel" message.
3. Repeat step 2 and either the inchworm or ducks should appear. Note, this need to be done before the ferris wheel is lit again, if you accidently shoot all the ducks, you need to start over.
One time the inchworm did pop his head out while the dummy was talking, never saw that happen again though. He quickly disappeared, we were shocked!
Let us know how it goes. Love that inchworm!!!