Tonight I changed the configuration of the aft throttle quadrant. I wasn't happy that light pressure on the aft throttle in the 'full open position' caused a slight over centre condition that was difficult to overcome with the front throttle. I decided it was best to return the control rod pivot point to the centre of the lever, shorten the flanged pivot fitting (to move the lever closer to the mounting plate) and to recess the pivot nut. This meant remanufacturing the stainless knob shaft and removing material from the reinforcing channel where the rod end passes. While I was at it, I added a plate to stop the bolt turning when adjusting the friction.
Unfortunately, recessing the nut reduced the pivot area for the bolt and caused a small amount of slop, so I'm still unhappy with the design and might yet start from scratch.
