The following is from the instruction manual
for the Expedition LX. It should be very similar to the Expedition LE.
"Stroller pulls to one side:1. The stroller is sensitive to the air pressure in the tires. If the rear tires do not have equal pressure, the stroller will feel like it is pulling to the side with the tire with the lower tire pressure. Check that the rear tires have the same pressure. Add air pressure to a maximum of 25 pounds using a bicycle style hand air pump.2. The alignment of the front wheel of the stroller can also cause the stroller to pull to one side. The stroller is designed so that the front wheel can be adjusted to correct for any alignment problem. Page 3 of the instructions
shows an expanded view of the front fork assembly. To align the front wheel, first loosen the wheel via the quick release handle as in step 2 of the instructions. Grab the front wheel directly in front of the stroller and push the wheel in the opposite direction of the pulling problem. You will notice that the axle will move within the slot on the fork. Move the wheel to the side a small amount. Retighten the quick release handle. Give the empty stroller a push across an empty smooth surface (let go of the handle) and note if the stroller now runs straight. Re-adjust the axle a small amount at a time until the stroller runs straight. Please note that a very minute
movement of the axle will affect the tracking of the stroller. Once you have aligned the front wheel, you can mark the holding plate position with a marking pen if you detach the front wheel on a regular basis. Please note that the hole in the fork is designed to allow the stroller to be adjusted to pull to the right, go straight, or pull to the left. If you continue to have difficulty with tracking, please call our customer service department at (800) 328-7363 for assistance."