[nerohedfrs]

What you are describing sound like (at least at the beginning) energy work-related vibrations, which feel slight, localized and like a hum or pulsing.
When I have good vibrations (in other words, unmistakeable) I have a generalized wave of very strong, loud and sometimes violent vibrations. On the lighter side, imagine having a beehive on your chest area. On the stronger side, imagine someone operating a jackhammer or lawnmower in the general vicinity of your chest. The most localized vibes are on the chest area, but sometimes they involve the whole body, and move in waves over your body. That's about how I can describe mine, when they happen.
I usually am in trance (with a few exceptions) when I experience vibes, and usually rope gets me out.
However, when I feel other exit sensations (not the buzzlike vibes, but the more seizurelike energy-body loosening sensations), then I don't do rope, but try something else.
As a general rule, I don't even try to get out if I'm not having some sort of hypnagogic hallucination, visual or auditory. Of course, sometimes I don't even have exit sensations, so I just test my paralysis by trying to get up. You'd be amazed at all the times this has worked.