Reddit mentions of Hitec 31311S HS-311 Servo Standard Universal

When you say the servo has stripped gears, do you mean internally, or the white servo arm that goes on top is stripped?

If it's internal, then another Hitec HS300 series servo should be fine as replacement.

In electricity, there's a lot of components that will require you provide a +5v DC signal, 5v is a standard that we've set. There's also a 3.5v standard which is more common in phones.

With the use of relays and additional power sources, you can control more power than that if you need to, though.

Just keep in mind that electricity is largely about tolerances. Just because you have a 5v line doesn't actually guarantee that it will always be 5 volts. There's a range that is thought to be acceptable. Seeing 4.8v, if I recall correctly, is still a "5v line"

Here's a pretty standard servo. It's not an "arduino servo" it's just a normal electrical component that when you apply voltage to its line, it operates. Since it operates in the 4.8-6v range, you can absolutely control this servo with the power from your arduino.

take all screws out and make sure the front piece almost falls off on its own

Get a cheap servo motor
http://www.amazon.com/Hitec-31311S-HS-311-Standard-Universal/dp/B0006O3WVE/ref=sr_1_1?ie=UTF8&qid=1411634957&sr=8-1&keywords=servo+motor

hook up wires to motor,
probibly a 5V motor so connect 3 AA batteries together for a total of 4,5V, connect switch

when actor bangs tv, someone presses switch, servo pushes top off TV

Budget: 12-ish $