Another update - the 20mm extra of the spring makes a huge difference - pretty horrible to cock and fire now as harsh and twangy in the extreme but after two shots the trigger failed to hold it for the next two...

New spring now out!

If I collapse a couple of coils to make it the same length as before (220mm) will it fix things and being a new spring still get the power back up?

Or should I just put the old spring back and add a couple of washers to increase the preload on that one?