Gimballing for my engines seems to quit without warning. I lock and free the gimbals but it doesn't help. Mods I have installed: AIES, Clouds and City Lights, Deadly Reentry, Kerbal Engineer, FASA, Ferram Aerospace, KAS, Procedural Fairings, KerbX, KJR, kOS, KWRocketry, Infernal Robotics, Module Manager, NovaPunch2, PlanetFactory, RealChutes, RealFuels, Realism Overhaul, Real Solar System, RemoteTech2, Realistic Tech Tree LITE + Tweak Pack, Stretchy Tanks, TreeLoader, and Universe Replacer.