Pitt--I fired up my Svea, and after running it a bit the cap didn't "phht" upon opening, suggesting it wasn't really pressurized, Most of the time I always used my mini pump, which would result in the "phht". Without it, the tank doesn't get pressurized, and only relies on the wick inside the tank. The prewarming just vaporizes the gas being wicked up, allowing it to work up through the valving. So, there's a possibility that something else is wrong with yours, perhaps in the regulator/valve. Of course replacing all the o-rings is never a bad idea. If you want to spend the money (available on eBay), the mini-pump considerably increases the output of the Svea. I used my Svea a lot in the winter on snow (putting a small piece of ensolite under it). My pump died years ago, and I was too cheap to replace it. There are a lot of Svea parts on eBay.