Most every “time & strike” clock has an “escapement” gear
like the one pictured below on the left side with the 12 slots in it …. (instead of gear teeth).
That “escapement” gear is what determines the # of “dings” per each hour. There is a “lever” that rests in the “slot” to prevent the gear from turning. When the minute hand gets to 12 the “lever” will rise up and the gear will start turning ….. and the “chime” will begin striking. It will continue to “chime” until the lever falls back into the next slot on the gear. Thus, the distance between the “slots”
determines the “# of chimes”.If your clock only strikes one (1) time on the hour …. then my guess is that the “escapement” lever
is not lifting up to permit the slotted gear to rotate. Thus the per se 12 o’clock “trip” for the “escapement” lever is probably fouled and/or needs to be adjusted. If the “escapement” lever is not working ….. it will only “strike” one (1) time on the hour.