parsley...are you sure you have the clock set to 9:30? Upon starting the puzzle it's set to 3:30...so you should click the face of the clock 6 times to get it to 9:30. And, you're sure you clicked on the valve lever on the hose of the bunsen burner (it's right next to the clock on the left). If those two things are surely done, when you click on the wind up car, it's sparks will light the burner. When it lights it, you'll see a small, skinny blue flame, flicker above the burner and in front of that Q of diamonds card.
If that's not working...there must be some sort of bug, or glitch?...I haven't been on these boards long enough to know if there is one or if others have complained of this as well with this game...but I'm doing all that right now, and it's working fine.
Make sure also that you've used the can opener that's hanging on the wooden fixture with a meter on it, above the manequin's head that's laying in the bath tub. As soon as you move the opener to the bottle cap in the upper left corner, it'll remove it ...then click the red wheel to the right of the bottle 2 times to rotate the bottle down so the liquid pours out. Now, if the bunsen burner is lit, and you have the liquid in the canister being heated up by the burner, you'll see steam rising out of the canister...that's your confirmation that you've done what you've needed to do to get the balloon to blow up (by pumping the bicycle pump 3 times) and float to the top to be pricked by the scissors. The rest is easy.
For others who've had problems with the balloon being blown up, but then shrinking back down...that's a sign that you do NOT have the steam rising from the canister, and that the liquid either never got poured into it, or that the bunsen burner was not lit to heat it.
Anyway...come back if it doesn't work or you have further questions, but I do hope this helps...
Edited on 11/06/2008 at 2:09:56 PM PST