So I finally got around to replacing the passenger seat tilt handle and cable unit in my Brera yesterday. It's a bit of a pig of a job, but mainly because I was having to figure out how to do it. Hopefully this brief guide will help others to do this - unfortunately I did not take any photos. I obtained the replacement handle and cable unit from AlfaWorkshop for about £70.
You will need to remove the seat. This is done by undoing the 4 bolts - 2 front and 2 rear, holding the seat runners to the floor. With the seat free, I then had to disconnect the two electrical feeds from the blocks in the floor before removing it.
I put the seat on a table to work on it as it is easier if you do this at standing height.
You need to remove the plastic seat base side panel that holds the other seat adjustment mechanisms as this covers the door side cable end. There are screws front and rear underneath, and a spring clip over the end of the seat tilt mechanism, that hold this in place. This should now pull away, but I also had to disconnect the feed to the electrical seat back tilt switch.
You now need to unclip the bottom sections of the seat back leather. The bottom side sections wrap around the back and clip over. Carefully ease these loose both sides. The bottom rear back section is also clipped in place. Again, carefully ease this loose so you can pull it upwards to expose the inside of the seat back.
You can now access the cable ends and the run of the cables inside the seat back. This is where I discovered why the top of the cables had snapped off the tilt handle. One of the levers which the cable ends are attached to was completely seized, and the other wasn't moving freely. So I freed these up with some WD40 and then greased them. With them now moving freely, it is easy to push them upwards to provide slack in the cables to release the cable ends - having removed the retaining spring clips first.
You now need to disconnect the clips that attach each cable to the seat frame. These are about six inches above the cable ends. You will need to push the side leather sections upwards to access them. They clip into a slot in the seat frame. You need to push them upwards and outwards with a pair of slim nosed pliers to free them.
The cables are also secured to the seat frame with a few cable ties - one half way up each side and one at the top. These need to be cut. The cables should now be free.
You now need to remove the seat tilt handle and cable unit. The plastic surround is removed by undoing the screw under the handle. The handle and cable unit is attached to the seat frame by two screws - one at the bottom and one at the rear. You will need to ease back the leather and foam to reveal them. Once these are unscrewed, you should be able to withdraw the handle and cable unit. Be careful to note and mark if appropriate the holes in seat frame that the cables go through.
Installing the new handle and cable unit is the exact reverse of removing it, ie thread the cables through the seat frame. Fasten the new handle and cable unit to the frame and replace the plastic surround. Refasten the cables to the frame with the cable clips and new cable ties after having reattached the cable ends and spring clip. Having ensured the new tilt handle and cable unit is worming correctly, reclip the leather in place, refit the side plastic panel and then reinstall seat in the car. You're done.