I agree with old sarge. Check your Maverick in boiling and freezing water. I thought my model 2 was way off until I did this and found that one of my Maverick probes was bad. I replaced it and all is now well.
I actually have two Mavericks. The probes look the same but they're not. If your probe needs replacement, make sure you get one for the 733. Maverick has all their probes available on their site.