With three cars and possibly two different ebrake setups available....I'm wondering is this a drum or caliper based ebrake? You mention replacing worn out pads, that'll only help if you have the caliper setup. In the 04+ with caliper setup IIRC there were a few folks that had to replace the caliper because the ebrake wasn't working properly in it. Not 100% sure though.
If it's a drum setup, pull the disc and look at the horseshoe ebrake and replace if necessary or adjust via the hole in the backing plate like Scott mentions.
