Provided the component parts are kept in good order, there should be little need to take the distributor apart except in cases of neglect or very high mileages, indicated by difficulty in setting the measured gap of the contact points accurately and consistently, often due to wear of the shaft or bushes. When wear occurs, movement can be felt when sideways rocking pressure is applied to the top of the shaft. The only solution is to remove the distributor and renew the shaft, or alternatively, renew the whole assembly, ensuring that the necessary parts are available. After removing the distributor, take out the contact points, then remove the driving collar from the bottom of the shaft, noting the orientation of the driving dogs in relation to the rotor arm notch. Clamp the collar in a vice, punch out the retaining pin, and draw off the collar along with the shims controlling the endfloat of the shaft. Carefully unhook the pull rod from the vacuum unit to the contact breaker mounting plate, remove the screws, and take off the vacuum unit, followed by the mounting plate and shaft, noting the position of the thrust washers. If the shaft is badly worn, it must be renewed, but check that the bushes in the distributor are not also worn; if they are, the whole distributor should be replaced. If the shaft and bushes are worn, it is likely that the springs and anchor posts of the centrifugal advance mechanism are also tired, so replacing all components is advisable. Avoid washing the bushes in paraffin or other solvents and ensure they are well lubricated before reassembly. New distributor shafts may require a variation in the thickness of the shims fitted between the driving dog and the body. Reassembly involves reversing the dismantling procedure, ensuring the driving dog is fitted correctly, and peening the ends of the pin to prevent it from dropping out.