I've got an 04 tundra that seems to have a mind of its own when it comes to 4X4. She'll go for weeks working just fine, right up till the time ya REALLY need it. I'm tired of it. You can jack the truck up and tap on the front actuator and she'll disengage. I searched the threads here and it seems this is a well know problem. Looks like it's time to go manual. I got a new actuator, striped it apart and I'm pretty sure it's going to be an easy job to convert it to manual operation. Make a new cover and a lever clamped to the gear shaft, operated by a twist lock cable. The gear shaft already has an O ring seal, add a compression spring to hold everything snugly in place. I'll pack the void under the cover with waterproof grease and it should be OK. Here's some pics, Stripped actuator, all the electric garbage I took off and the piece of 3/8 thick aluminum plate I had laying around that's soon to become the cover and anchor point for the cable.