funnily enough, being in the RAA side of things now, the Hydraulic lifter Jab engines are pretty reliable and not know to have failures. the reputation of the new jab engines are they are pretty bulletproof.
i have heard rumours around the traps its the operators of the jabs either in maintainence or the pilots themselves not operating the engines as per the manual. as the cases of engine issues with this operator are abnormally high .