Murray self propelled 5.5hp mower

Mower is runnig fine, belt is ok and pulley is spinning but mower is not pulling at all. Murray model 226111x92b. How do I fix the self propel? The front wheels wont turn at all.

Took everything apart, oiled the axle bearings, checked fluid level in speed reducer on axle, cleaned everything up and put it back together and is working great now. Just need to get a new cable for it, and it's good to go. Turns out everything was just froze up and needed a little tlc and some oil to free everything up.