Stuart,

The last time I did this on a 55, I removed the quadrant because it was easier to do with the quadrant removed. I believe you might be able to do it without the removal, but that will depend on how your quadrant is installed and what exactly it is installed with. For instance, you have cable steering from the helm and Joerg has hydraulic steering from the helm. There is a significant difference in what is connected to the quadrant.

If it were me, I would remove the quadrant, then remove the locking plate circled in the picture below.