There are a few places the e-brake can sieze up. The first place it can sieze is the lever-arm under the cab under the passenger seat. But if that siezes, it normally pulls both rear cables tight, not necessarily just one (it depends on how balanced the rear cables have been adjusted). The next place they like to sieze up is at the drums themselves. It's a bit of work do to, but it can be cleaned up and anti-siezed to last a couple years (here in the rusty north) before more maintenance. I normally have to touch things up once every few years. The arms that the rear cables connect to at the drums are steel, but the small housing they run through on the outside of the drum (has a rubber bootie over it) is aluminum, and things corrode here. If this does not move freely, it is likely what is seized. In order to fix it, I often have to take the lever off, which requires disasembling the brakes and removing two 10mm nuts and disconnecting the parking brake cable. In the worst cases, I've had to bash the lever back and forth with the aluminum housing securely in a vice. And in the worst of those cases, I've busted the housing. You may want to try pulling up the rubber bootie first before disconnecting or disassembling and see if you can free it up (lots of lube too).
In addition to this lever arm, there's a small rotating "v" shaped bracket inside the drum that connects on one end to the lever with a short cable and on the other end to the rest of the braking system. Chances are, this is siezed up too (though it's much easier to unsieze).
Once it's all freed up, make sure to put some antisieze on the lever arm and housing, then pull the bootie back down. Then, make sure to use your parking brake regularly. It helps prevent any buildup of rust, and once every year or so, check to see if it needs more antisieze applied. Also, the use of the rear parking brake is what adjusts the rear brake pads, so if your parking brake hasn't worked for a long time, your rear brakes might not be functioning at their best.
Furthermore, if your rear brakes aren't engaging anymore because the parking brake is out of commmission, you'll want to read my article on rusty rear brake lines:http://www.geocities.com/toyotashawn/brakes.html
4Crawler--too bad you don't have to deal with this in sunny cali!