The most common problem when moving a pendulum clock is the clock is not level in the new position. Before doing anything mechanical, check the level both left to right and front to back. The clock must be level to run properly. I find the easiest tool for doing this is a small button level available at most hardware stores for under $2. Set it in the base of the clock and just adjust the clock until the bubble is centered. Some clocks have adjustable feet to aid you. Otherwise any small wedge placed properly under the feet will do the trick. Test by gently swinging the pendulum and listening to the ticking sound carefully. You should hear an even "beat". (Not louder or longer on one side than the other). If the beat remains steady for 1 minute - you've got it.
Bruce Olsen
February 2008