bump these replies.
I would also drop the smith machine for benching if not for everything, it's putting your body into a strict 90º angle on all of your movements and your body is not designed to go straight up and down, when you fatigue you should naturally find slightly different variations or grooves for your arms to follow, your body will do this on it's own by slightly splaying your hands in and out.
drop the smith for a few weeks and you'll recover quickly