I have had similar problems, and found one helpful solution. If the pressure cooker is leaking steam (especially around the valve) and the yellow indicator won't come up, try pushing up on the lock switch. I found that just giving it a little nudge further towards the lock position caused the seal to set and then the pressure cooker came up to pressure. Now, this was about a year ago that I discovered this, and haven't used the cooker since that time. Today I pulled it out, and am having the problem where it leaks steam out of the gasket by the side safety valve! I'm guessing this is from a misaligned gasket as other responders have indicated. However, the yellow indicator is up and pressure is building to a "level 1" setting, just not "Level 2". Oh well. Time to keep experimenting!