The cage is designed to spin. There's a slot on the cage that compresses when the connector is inserted that should create a positive connection with the center post. These aren't designed for high amperage draws. If you run them in a high amp system, they heat up and start melting your battery case.

Granted the solid connectors are the better ones, but you might have something else going on causing your issues.

You sure you're not just temporarily loosing power to the receiver and therefore having a temporarily disabled vehicle? Super common with Savox servos and other high draw servos. Might want to try a capacitor/glitch buster on the receiver.