JD 115 front wheels toe in?

John Deere 115 lawn tractor front wheels toe in. Turns too far right, not as far as did left. Makes steering problems and excess wear on tires. Steering wheel attached to column with gear at end (may be worn?) Meshes with pie shape plate attached to "tie rods" (one to each front tire-not joining 2 front tires like normal tie rod). May be gear on steering column, bent "tie rods" or bad bearings in wheels? Tractor only 3 yeas old. How do I tell which, how to fix.