Read the behavior as a signal
Two-second, four-second or other unusual stepping patterns can be built into a movement as an end-of-life or low-charge indication.
Solar watches need charging before parts
If the watch is light-powered, give it the manufacturer-recommended charge before replacing components.
A new battery should restore normal stepping
If a conventional quartz watch continues abnormal behavior with the correct fresh cell, more diagnosis is needed.
Tell us the exact pattern
How many seconds each jump covers, whether the watch keeps accurate time and what happens after charging are all useful clues.