Another way is to drill the hole oversize and insert a dowel, then redrill for the proper size hole. I've used this repair for anything from servo holes that stripped to wing hold downs to plugging old attach holes in the firewall when installing a different engine. And I use epoxy to install the plug just for added security.

If you're just relying on plywood to hold the servo, back it up with a piece of wood - spruce, pine, or something that is a bit stronger than the ply.

Hogflyer