I realize that what 4*60 says is true: "To repeat +1/4-3/16 = +1/16." I meant to say this would be the ideal solution if redrilling holes could easily be done.

Perhaps filling the existing holes, knocking out the blind nuts, and trying to start over again a little forward on the mounts is what I will have to do. However, I anticipate many frustrating hours of work.

The current holes are tapped all the way through the plywood doubler and the spruce mount, which is something I could not duplicate on my new holes because I don't have the space to work or the tapping tools available.

In order to remove the blinds nuts already there, I think I will have to drill the existing holes out to eliminate the tapped threads, install the mounting bolts again, then tap the blind nuts out using the screws and a hammer. I tried tapping them out as they are, and I am afraid the plane will suffer damage before the nuts budge. Those threads in the wood add a lot of strength and holding power, which is one reason I don't want to redo the mount.

Tyler