There is no hole drilled in this gear where it is attached to the distributor shaft, this has been the case for the last 10 years, reason being: no two distributor shafts are the same as far as the positioning of the hole for the roll pin is concerned. The distributor and the new gear should be taken to a machine / engineering shop where the hole can be accurately drilled in the gear to suit the position of the existing hole in the distributor shaft. It has been known to happen when a pre-drilled gear from another distributor is fitted to the distributor shaft, when the roll pin is being tapped in and the holes don't align perfectly the gear can crack.