Fastback,
When you go in that hard it is common to break things, even servos and radios.
There is a high probability the circuit board is broken and/or some gears.
Servos aren't very expensive, my suggestion is to replace them if they aren't working.
Why take the chance for $12?

As for missing parts I doubt it. Sometimes boards are designed for multiple applications.
This one probably doesn't need a certain part so it was left off.

Good Luck,
KW_Counter