In the older clocks they had a strike system called a "count wheel." This can get out of sink easily. You should have a wire hanging down from the count arm that you can push up or if you do not have this, you may be able to turn the minute hand back to 20 till the hour and then back up to the hour to make it strike. Be careful in doing this, if you get resistance turning it backward then stop, the clock may not be designed for this and you are just missing your wire that I mentioned above.
Once you find out how to make it strike, continue to trip the strike until the number of gongs equal the time of the hour hand.
Stevens Clocks, June 2009