Quick Servo Question

It'll still work .. 5 volts and 4.8 volts isn't a big difference.

I've used tg9e servos in my Hearoid... although now replaced for high torque (weren't man enough to lift the lower arms or hold them and some angles. Voltage wise they work fine.

In fact, I use them to rotate the hands and they are great...

so they should be fine for a wall-e head horizontal?

If you mean for the pan then yes it should be fine. You may want to check about the tilt through as they aren't the most powerful of servos but Wall-Es head isn't that heavy.