Replacement Servo???

[MicroSpeed]

I am in need of a replacement servo for my Xmod, the gears keep either getting out of place or they're sheared, but it gets very annoying to keep popping them back in place, a process which takes 2-5 minutes, and has to be repeated every 1/2-2 minutes, whenever you steer sharply or run into something. Can I get a replacement servo from RS, or if not, who make one and in what size could I get from TowerHobbies?

Thanks,
David