Matzo Ball soup - not like mom's

A couple of weeks ago I made a batch of Matzo Ball soup, using a box of Manischewitz Matzo Ball & Soup Mix. I hadn't had it in a long while and it wasn't bad, but sure wasn't like mom's. Actually, the broth was pretty darn close, but the balls, well, they were light and fluffy. I don't like them light and fluffy. Mom always made them, um, differently, far "firmer" - we called them "cannon balls"! I love them that way, but I can't figure out how to make them so.
Anyone have any idea how to make hard matzo balls? Leave me a comment!

Enjoy,
Lorence