I recently done a service on a hynudai i30 and found a bad knock in the steering. Removed airbag and steer wheel

Note the Genuine Hyundai coupling part number is : 563152K000FFF, if the only solution is to replace the whole steering shaft, then why do they list a part number for the faulty part at question? 

So I removed the steer shaft mounts and wiring and with a stethoscope pinpointed the knock. Arrows show location

I30's have electric power steer motors, the knock is between the motor and retainer where it joins to the shaft. The whole shaft was removed and placed on my bench. See below pic and arrows mark the spot.

After placed on bench the electric steer motor computer was removed, note: Take care unplugging the computer as the pins are fragile.

I removed the electric motor, and the plastic coupling was perished, see below, note the arrows, this is supposed to be a sprocket.

I laid the new coupling with the perished so you can see the diffrence.

Make sure you remove all the perished plastic and insert new coupling as shown, do not use any solvents as it may damage the circuts, compressed air is the best bet.

Re-assemble, do not lube the new coupling, make sure you align the coupling so the motor installs with ease. Job done, this took me 3 hours, and hour to remove, and hour to replace the coupling and an hour to re-install. Hyundai do not have a re-call in place for this, in my opinion it should be re-called as there is an upgrade available for this fix, but Hyjndai would not let me see the paperwork. the coupling itself cost's $4.50. 3 hours labour but to my understanding Hyundai charge more than 3 hours. My warranty is the same 12months / 20 000k.m. Warranty using genuine parts.