how can I fix the boiler seal on my espresso maker?

We have a new "Capresso" brand espresso/cappuccino maker that we got for Christmas. It has worked very well, and is still working well except that the pressurized chamber seems not to be sealing perfectly any more. After the water heats up to full pressure, and especially during the process of steaming the milk, bubbles are forming around the top seal (where I screwed the top back on after adding water). I suspect this is because the rubber gasket that fits up inside the boiler cap has gotten out of alignment (it's actually not rubber but a translucent rubbery plastic material). At some point in the last few days the gasket came out, and I wasn't sure how to reinstall it. There are two knobs or bumps on the gasket, that look as if they are meant to line up with 2 holes in the metal part of the boiler cap itself. Right now I have the gasket installed in the cap so that those knobs are "upside down" -- i.e. they face downwards when the cap is installed on the machine. Should I take the gasket back out and reposition it so they engage with the holes? Will this fix my steam-leakage problem? Right now I am still able to make good lattes and cappuccinos, but I am afraid if I don't address this seal problem I may begin to lose a lot of pressure.