Hi Carol
If a good clock repairer can't get it to keep going there is either a very obscure problem, or he isn't that good. If the clock has a pendulum set it swinging and listen to the tick, it should be nice and even. if it isn't try lifting the side with the longest pause by placing a piece of cardboard under that side. Once the tick is even make sure the pendulum is swinging freely and not scraping on anything. Failing that send it for repair.
clockdoctor, October 2010