I am guessing the springs failed first but not necessarily at the same time. It is hard to see in the photo's but the springs were quite rusty from trapped condensation within the valve caps. I would say this is due to the moisture absorbing characteristics of castor oil and Methanol fuel. It was only on the inlets and not the exhausts, suggesting that the extra heat from the exhaust side of the head is enough to retard the condensation build up. I will need to somehow vent the caps so this does not reoccur, given the location of the caps under the UFM it is something I should have checked earlier I guess. I certainly jinxed myself, as I have always maintained to everyone how reliable the machine has always been, but luckily the damage is only superficial and easily fixed. I had put some location marks from the cam to the wheel, and these look to be still in alignment. I removed the barrel from the piston that got clipped by the valve, and it all looks fine, so I would say the cam copped the brunt of the shock load through the valve train. I have replaced the springs and reassembled the heads ready to refit to the engine, and I will replace the cams/followers in the next few days, as I don't want the bike in bits for very long.