As many of you know the Plessey Gear Actuator is no longer made. The back-spring is also no longer available. I just removed mine and replaced it with a rebuilt one assembled by Top Gun. Mark from Top Gun says they have parts for only one more rebuild. A new Eaton gear actuator is about $15,000.
My gear actuator has 571 hours on it since back-spring replacement, so there is still useful life remaining. I also have a spring from the last replacement.
If anyone is interested in these for any reason, make an offer off forum.