Gates Carbon Drive single speed shows inconsistent tension
To my awareness, the Gates-ness won't introduce any factors here not present in other single ring, single cog bikes without chain tensioners, other than making it way more expensive to do any replacing of drivetrain parts that may wind up being needed.
One of the questions in this scenario is whether you have reason to suspect the increased tension spot was acquired in use, over time, or by violence, versus occurring immediately after wheel re-installation. Concentricity is never perfect; if the tight spot started after the belt tension was re-established either from the wheel being off or sliders being adjusted if applicable or anything else, it's likely that donking the wheel forward a bit will make things how they were, i.e. there will be a tightest spot that you just don't notice, which is how all bikes without sprung tensioners are.
If the &quot;front pulley&quot; (Gates speak for chainring) was damaged from impact, something like this can result. You'd likely be able to see it by backpedaling the bike while carefully observing it turn against a fixed reference point. They're stiff and need their dimensional precision, so you should probably replace it if you find significant problems. If the tight spot is always in the same spot in the crank rotation, it's not the rear cog unless the quotient of the front and back teeth count is a whole number. It can be then.
The last avenue is messing around with improving front concentricity by trying different spindle positions, especially if the cranks were removed and re-installed recently, or squirming the &quot;front pulley&quot; on the spider tabs, which is kind of the most likely cause and fix of the whole problem if other mechanical changes or a traumatic event didn't precede the issue. Barnett's is a good reference to read about procedure for the former and Sheldon the latter.