Help--B with belly mower blues

 

 

At first I thought that the deck was not leveling out due to the slope, but as you can see in the next picture I have the same issue on the vertical runs too:

 

 

Being fairly new to tractor belly mowers, here is what I think could be relevant info: I am running new blades (universal/edge on both sides), the deck and blades look level (eyeballing) on the shop floor, I mowed most of the wide open spaces in second gear, the (new) belt tension did seem loose when finished.   I had tightened the belt up to correct tension after a half hour as the manual said, and didn't think to check it till four hours later, when I was done.  I am running new Ag and ribbed tires with wheel weights.  The mower discharges on both sides as a previous owner has removed the side panels (I keep the kids far away when I mow).  The grass wasn't high at all, maybe six inches.  All the spindles spin and take grease.

 

The good news is all the streaks cleaned up with a second pass, and I got to spend quite a bit of time out on her today.

 

So, could a loose belt cause the streaking?  Could my tires be mashing the grass down and the universal/non-lifting blades not be picking it up to cut?  I'm not sure what to look at next.

The bades with lift work better. 2nd what Bill said, don't let the grass get too high before mowing as it will "pack down" under the tires and not cut as cleanly. I have a CA with the L306 mower and use the Gator blades. I run in 3rd gear and 3/4 throttle.