If your harness straps appear to be uneven, this is most likely due to the strap getting twisted or stuck somewhere along the way.
Unthread the harness straps: Disconnect the straps from the Metal Harness Plate and pull them through the front of the seat.
Re-thread the harness straps: Feed them back through the appropriate Harness Slots (AT or BELOW shoulders for rear-facing, AT or ABOVE shoulders for front-facing), then re-attach them to the Metal Harness Plate, making sure there are no twists in the straps.
Check behind the seat, where the bottom of the straps feed through behind the seat cushion where the straps are secured using anchor plates.
Ensure that these anchor plates fit snugly into their grooves and are not getting snagged on any piece of the seat frame or shell.