Hi Alistair, I have tried all the usual suspects from my pellet selection and no real joy. Any how, this morning I could down the spring by half a coil which dropped the power from 11.6 to 10.2. Added a washer which pushed it upto 10.7 and decided to try it at that. Happy to report that accuracy is now restored and sight picture much steadier on firing.I will be leaving it at that power now, i guess 11.6 was pushing it too much for the short stroke.