Just to go the other way, I wouldn't do a build without pulling the seat. If you look carefully at the cut away photo that Retro kindly posted up, you can see there's a lot of 'dead' area around the seat and often, there's all kinds of crud and half the dead sea residing in there.
You can leave it and run the gauntlet but if you do pull it out, then you can see and you'll know for sure.
I wish to object !
All this use of the word "Dead", is not mere inadvertant innuendo; it is prejudicial against elderly users of this site, who don't need reminding that they probably won't live long enough to complete all the things that they would like to do to their Minis.
Lol.