Hi Paul, When the clock is started, listen to the tick. What you have to do is set the clock on a known level surface and when the clock has settled down, say about 1 minute, the sound should be an EVEN tick-tock. If the sound is not even then the clock is not level, or the setting of the escapement has been altered. Moving the pendulum up or down will only alter the timekeeping, ie make the clock go faster(up) or slower(down). Unfortunately if you have had the clock serviced, you will probably need to take it back to the person to reset the timing. Explain your problem and you may be given more advice. A sound piece of advice: NEVER move a pendulum clock without first removing the pendulum, otherwise you may alter the escapement setting or worse still damage it beyond economical repair(cheap clocks).
Good luck,
Richard
Richard de Verteuil, November 2007