This page describes an alternate technique for drilling the holes in the heatsink. If it works out I'll update the manual to reflect this method.
Step 1: Print out the template located at the bottom of the page. Use the dimensions on the template to verify that your printer as printed the image the correct size. If not, it maybe possible to scale the image correctly in the printer setup.
Step 2: Cut out the template as accurately as possible. Use an Exacto knife and a straight edge or accurate scissors.
Step 3: Apply glue stick or some other easy to clean adhesive to the back of the template.
Step 4: Stick the template to the heatsink making certain to line up the front edge as marked.
Step 5: Mount the front panel and plug in the amp board and check to make sure that the hole marks line up correctly.
Step 6: Remove the amp board and front panel and mark the holes with a center punch or nail.
Step 7: Remove the template and drill the holes with the included drill bit (#43).
More detailed instruction on the way...