Well...doing process safety management and predictive maintenance on commercial turbines vibration analysis is common. Only thing is, the equipment is slightly more advanced...with software.

I've seen others use this technique as well, actually and it has basis, but maybe not merit. I do know people have identified bearings about to fail this way, but seems like you're really pushing maintenance limits, because if you can tell from vibrations you can feel, how close do you think you are to catastrophic failure? Wonder if portable vibration monitoring equipment has a place here? Keep tracking from known good readings and track vibration amplitudes...