Drill the holes out larger. You can use a mild acid like in Aluminum
jelly
but the corrosion gets into the metal and makes it extremely brittle. The
holes would crack out under stress.

In fresh aluminum, use NoAlox or some other type of antenna grease. I
find
a little extra Vaseline in the mix helps. The idea is not to mess things
up, but just rub enough in to seal the pores of the metal.

I agree with the NoAlox but I reserve comment about drilling out the holes
until you clean it first to see if it needs drilling out.
You can pick up NoAlox, or Penetrox in the electrical dept of Lowes or Home
Depot, or at an Electrical Supply house like Graybar. It is used by
electricians when making electrical connections with Aluminum wire. It
contains an abrasive to cut through the oxide, and the grease to coat the
aluminum and keep O2 from it.