"Wall.e is a fantastic model, and it is a shame to see some focus on the neck joint. My wife suggested a simple and inexpensive solution to provide some friction in the neck joint: PTFE tape (used to wrap pipe threads in plumbing; I don't think it will harm the Lego brick as it contains no glue and is easily removed). Some experimentation is required regarding the optimum number of wraps around the pin, but you will be pleased with the result and then able to enjoy this incredible model as it was intended.
Wall.e contains some of the most clever building techniques I have yet seen combined in a single Lego model: from the use of rubber grommets to provide friction in the arms to the very complicated eye pieces where studs are facing all directions. This set is a bargain for the price, and a very entertaining build. Highly recommended."