After a long winter and very cold spring it’s finally ready!
Have you done any work on the linkage pivots? I found that the bearings in mine weren't installed with any loctite, just a circlip spring. There was about 1cm lateral movement in all of them.
Even after fixing that, it still seems like the manufacturing tolerances are just a little off. I've had to install some .5mm nylon spacers inside the pivots to take up the extra play.