I use Helicoils (usually 30 mm dia.) in my work and have had good luck with them. Be sure that when you drill the new hole that it is square (aligned in both planes) with the old one. Check with a machine shop that works with aluminum about the drill bit. Standard bits must be reground to a different angle when drilling non-ferrous metals like brass. I don't work with aluminum so I don't know if bits must be altered for it.