I was posted to Cottesmore Armoury in 1961 just as YS1 was replacing Blue Danube. YS1 was definitely user unfriendly. The collapse of the chamber which the ball bearings occupied was a vital part of the chain reaction which is why the balls were there.From memory when the bombed up aircraft went to 30 minutes readiness the bomb was lowered and rolled over and the balls removed.When the readiness returned to 40 minutes the balls were replaced. It was not unknown for some damage or problem to occur in all this and so another serviceable aircraft would have to be bombed up.
On a Mickey Finn exercise we were at our Boscombe Down dispersal when the bomb carrier was damaged and so a pantechnicon was despatched from somewhere in Kent complete with police escort and the bomb was returned by road. YS1 also required heating blankets to keep the temperature stable so the poor armourer who checked it every hour did not get much sleep. YS2, when it came along, was a much more user friendly way to end it all.