How do I pull out the steering column on a 917287140? There is a plastic bushing which seems to hold it in.

Hi,
The steering shaft comes out through the bottom.
Everything from item #21 upward must be removed with item #72 being the bolt that holds it all together. At the bottom item #64 is a clip that holds everything at the bottom and the 2 bolts, item #28should be removed. Picture is below.
If you wish the manual, take this link:
http://www.searspartsdirect.com/partsdirect/part-model/Craftsman-Parts/Riding-mower-tractor-Parts/user-manuals/manual-downloads/Model-917287140/0247/1509200?modelNumber=917287140&diagramPageId=00003&documentId=P0804121
And click on Download.
Peace,
Clarke