We had a thread a while back on "jack stall" and there were some magnanimous ppruners who thought that when the servos stall (because they are not powerful enough to overcome the blade forces) that this was a "good" thing because it kept the rotor controls from being over stressed.
This is a film of a dauphin (one of the type helos that are jack stall prone) experiencing jack stall, going out of control, but being recovered by the pilot when the rotor forces subside enough to allow the cyclic to become effective.
Another name for jack stall is control lockup, and another is servo stall.