Ron Micjan said in another post that it was due to disconnecting the swagelock underwater... and that quite a few people have been suffering from it recently, myself included.

I suppose if you do disconnect in saltwater it should be flushed through with fresh afterwards, but this would require pressurising some freshwater and connecting it to the swagelock and letting the solenoid fire so I guess nobody bothers.... ??

I am sure you will get it down to under an hour after a couple more goes mine has easily done 30hours since the last strip down and is still sounding responsive, when it starts sounding sluggish I know it is going to jam soon - mine has only ever failed closed though which I have been glad about