I decided to use some scrap aluminum that I have laying around to see what a shim might look like for the HS-404 problem I have.  In the first picture you can see the slight mis-alignment of the holes in the HS-404 and the front spar…

Here’s the shim I made from scrap aluminum:

And here is the shim between the HS-404 and the front spar:

After I made the shim, I posted to Rivetbangers and decided to mull over the problem a little more as I did some more work on the stab.  I match drilled the entire right horizontal stab with the exception of the HS-404 (due to the above).  The outside portions of the HS-810 and HS-814 reinforcement pieces still need drilled as well.  I took the stab back apart and deburred and scuffed all the parts in preparation for priming.  I’m going to do the same thing for the left side, and by the time I’m done, I should have come to a decision on my two problem parts.  Right now I’m leaning towards replacement.  While there are a few very workable solutions, I don’t like the idea of compounding errors.  In the case of the HS-404 we could potentially have the shim AND the mis-aligned holes.  Aligning the holes may very well create another problem… edge distance.  With regards to the HS-405 on the other side, Mike Bullock’s solution may well be the way I go… re-drill, maybe add a third rivet, and press on.  I assume you have to pay attention to edge distance between holes as well…

Here are pictures of the prepped parts ready for priming: