I had to do the same corrections on the left main spar as I had to do on the right spar.
First I had to remove the AN3 bolts and doublers. I had to use quite some force, when measuring I noted 61 inch/lbs which is more than I expected because AN3 should be torqued to max. 25 inch/lbs. I will ask TAF about the torque value for these bolts.
Then I drilled the missing hole in the splice plate and removed the rivets of the spar extension. This spar extension is not anodized, so there is no corrosion protection between the mating surfaces. Now I can spray both parts with epoxy primer and rivet them back together:
Next is priming the main spar.