Kent,
You should probably do a sanity check on the installation before you go any further. Check to see that the shoes are seated correctly on all the contact points including the parking brake crossbar. Make sure the springs are holding the brake shoes all the way against the center post and into the cylinder.
You can't damage the drums by turning them, however the more times they are turned the more material is removed. There are limits on how much can be removed, usually .060.
Fred
