Toro 52" Cutting Poor

I have a Toro Z Master Z149 52" Model 74173.

Problem is it's leaving a LOT of the grass uncut after I go over it!
I sharpened blades and tightened the belt and it's not doing much better.
Any ideas? Are there supposed to be some baffles or something under the deck? Does anyone have a picture of the bottom side of this deck they can attach?
Any help appreciated!

Thanks!