I have been trying for some time to get our clock to keep time correctly. As I finally seem to be getting it slowed to where it needs to be, it begins stopping sporadically. I do notice that at times the tick tock seems to almost skip, or at least that is how it sounds. I'm not sure if that is an important indicator or not. We have had it in to a clock repairer a couple times over the last few years and this time I am having problems getting it to keep time correctly. I love the old clock, from my wife's father, and would appreciate any thoughts as to what I may be doing incorrectly.
The clock beat should always be even and and one skipped beat can stop it. I need to know if it only skips a beat when you have it set at or near the slowest position. Also, be sure that the clock is wound up. Your clock probably has a fixed pendulum, meaning there is no adjustment on the pendulum its self. I'm assuming that you are using the small key hole in the front of the clock to make the timing adjustment. This adjuster moves a finger along the pendulum suspension and might be causing your problem as it gets near or at one of the extreme positions. Without inspecting the movements I can't say what is making it stop but this is where I would start: Turn the timing adjuster a couple full turns toward the fast position. Wind the clock. Listen to the beat and see if the clock will keep running. If so, I would replace the suspension spring. There is a universal suspension spring for $.80 that should work on your clock. You would cut it so that its about 1/4 to 3/8" longer than your original. This would allow the adjuster to stay near the middle of the spring (where it should be). I don't know what your repair person did, when it was done, or how much you were charged for the work. If you had this problem from the start (not keeping time) you might be able to have this work done for a nominal charge. Any reputable clock repair shop wants to keep a good reputation and is willing to work for it. It's a quick repair for an experienced person to make. A bit involved for a novice.
www.norkro.com clock parts and repair