Okay - be very that the movement is due to the column and not vibration somewhere else being transmtted through the steering column.

Now, in answer to your question, the shaft needs to be taken off the rack. Undo the bolts that hold the top of the rack to the dash. Take off the plastic covers over the indicator stuff and undo the screws that hold that to the column . Dont worry about the steering wheel it can stay on the column. Then lean down and the steering column fits onto the rack and is located by a splined male and female shaft. It is held in place by a 7/16 head sized bolt that passes throught a cut-out in the rack protrusion. Remove that bolt. The shaft should then slip off the splines and be free - brute force is not needed and will only do damage to the splines which are soft steel not hardened steel. It may need some effort but not brute force.

With the shaft out - you will see the clamp that holds the splines on the rack splines. Undo the lock blt on that and then you can withdraw the shaft entire from the column cover. Slip the top and bottom nylon spacers out and replace them. Either with replacement spacers or with some else that will do the job.

On reassembly - the steering column entire should just slide down over the rack splines. If not find out why and adjust - perhaps - the angle of the rack by undoing the four nuts that hold the rack to the car floor. Do not - do not do not - hammer the shaft onto the rack splines. The outcome of banging the shaft is to find a bag full of steering nothingness as the splines strip under a heaving steering load. Centre the steering wheel and the column before you slide it down, of course

Good luck