This is very common on all types of reel mowers. Even huge golf course reels have this. You would need to determine whether it's suddenly developed an alignment issue or whether the reel has gone cone shaped from a previous alignment issue. For something like a Scott's, it's probably cheaper to buy a new one

if you do a reel to bedknife adjustment and it still cuts un even, probably time to get a new mower. Golf courses would grind the reel , and install a new bed knife, but for your application, better to just get a new mower.

How long have you had the mower? Also just to clarify, the mower at one time when you first got it, did strike the bed knife correctly or similarly all the way across, or is this something that you have always noticed was not proper?

Also have you done the paper test for the blades and on left middle and right side of bedknife?