How should a grandfather clock be properly serviced?
With only a few exceptions, all movements (the working part of the clock) should be taken completely out of the case and the dial (face) of the clock removed so it can be properly oiled. If someone tries to oil it just from the openings on the side of the clock, it is almost impossible to get to the pivot holes and levers that are behind the dial (face). If a service man does this, show him to the door because they are only oiling half the clock and paying for that is a waste of your money.
