I've got my top end back together and my o-rings don't seem to want to lay down nicely in the grooves. They pop right out as if they are a wee bit small in diameter. These are 10 years old. I got them from Jim when I bought the bike, and unwisely waited a decade to pull the jug. So, maybe they shrank a bit. I dunno...
I'm thinking of a drop of candle wax here and there to hold them down.
Edit: 2001 xc300