I've just bought a Drangonfly 22E and I think there is a problem with either the Transmitter, Receiver or one of the servos.

I''ve tried to swap over the servos to test, but I can't unplug them from the receiver. There are 3 plugs in the receiver and they all come out about 2mm and then seem to jam on something. Am I missing something here or should they just pull straight out?

Thanks
Anthony