Trouble Shooting Uneven Cut

[Ching-A-Ling]

I am getting an uneven cut on my 2007 Dixie Chopper; I grew tired of keeping up with a slow leak in a front tire so I upgraded to the 'never flats'; I've checked the rear pressure and up to spec.

It seems like the 'lower' cutting blade is the front left (as you are sitting in the seat looking forward); I have never replaced belts; I have adjusted the tension on the two places according to spec. Belts don't look bad, but I have purchased replacements and have them on hand should i need to (just thinking that I'd rather not screw with the belts if there isn't anything wrong).

Is there anything else that a do it yourselfer should try before I go borrow a trailer to have someone look at it?

Mower is a residential use and only has 300 hrs on it.

Thanks in advance for your thoughts.