I had mine all apart earlier this year, so if is sort of fresh in my mind. It seemed a lot harder than it really was. I ended up using the point of a test light to push in the brass tab. That was the part that stumped me the most. When you get down to the very guts of it and see all of the channels for the air venting be careful as there is a lot of fragile stuff in there. It really only goes together one way but there is pretty much a certain order that it all has to go.
BTW, I thought at the time that I had no vent and I don't think that I did. But now I believe that the real issues was that we were running out of gas AND our screen on the tank petcock was plugged.
But, your not having that issue as you are talking about paint, so all you really want to do is get the chrome cap off and not take it apart. Mark has you on the right track, he helped me with mine and sort of talked me through it and bolstered my confidence!
It was a little difficult getting the cap back together with the spring tension. Push it in and twist it past where it should really be and it will catch on the little latches. I'm guessing if you don't get there spring latched it will rattle like mad.
The other thing that Mark mentioned was to make sure it is locking and UNLOCKING before you put it on the tank and close it. Make SURE you have it together right before you close it on the tank.
