Beach rear head rest broken

[PhilG]

Hi

In haste I leant over the middle rear head rest when it was at its half way setting and put my whole 12.5 stone body weight on it to reach something in the back.
Unfortunately I seem to have broken something inside as the headrest will not now sit at different heights. I guess I have damaged the ratchet system inside.

Does anyone know if this can be easily fixed (I am no mechanic but am fairly competent).

Cheers
Phil