My pendulum clock does not keep time
If your clock is slow (loses time), turn the nut on the bottom of your pendulum to the right. This will make the pendulum shorter
If your clock is fast (gains time), turn the nut on the bottom of your pendulum to the left. This will make the pendulum longer.
Rule of thumb:
Up = speeds up
Down = slows down
My battery clock is not running after I changed the batteries
It sounds strange since you just got new batteries out of the package, but make sure that they are new batteries. Sometimes stores have batteries sits on a shelf for years. Investing in a battery tester is not a bad idea.
If your battery is fresh, but the clock is still not running, make sure the battery contacts are clean. If your clock takes 2 C-cell batteries, make sure you have used Duracell batteries. If you are using Duracell batteries, then follow the steps described before.
If everything seems good but the clock is still not running, most likely the movement will need to be replaced.