This most recent MTS is CRITICAL in answering your question. One particular detail I liked was the idea of the "Electric Moment of Truth", where the electric chairist is working to bring the leg from his bicep to the shoulder. The "Moment of Truth" component is new for me, I've never heard it referred to like that before. It helps you appreciate the concept that you NEED that leg on the shoulder to complete the standard, textbook electric chair. As the guy on top, you can sprawl backwards and bite your knee on his bicep, making it really heavy. The episode talks about options from here, including the electric stone sweep. However, if you sprawl and keep your leg off his shoulder, this can buy you time, maybe allowing space you to grab his head to slow'em down, and eventually fedangle outta the position. Keep this in perspective of the bigger picture though. Such measures are only necessary if you've lost the electric underhook battle and he's pretty much 80-90% there, in the RED ZONE, if you will. He's got the ball on your twenty yard line. You could've kept the ball on his side of the field by not losing the underhook battle and not letting him swim under you to control your hips.
Watch the episode for sure, if you haven't already. Well worth the time investment in the long run in increasing your awareness in this position.