“When do clocks die?”/“When their time is up.”

A clock riddle is:
 
Q: When do clocks die?
A: When their time is up.
 
The joke has been cited in print since at least 1976.
 
   
Google Books
Biggest Riddle Book in the World
By Joseph Rosenbloom
Illustrations by Joyce Behr
New York, NY: Sterling Publishing Company, Inc.
1976
Pg. 184:
When do clocks die?
When their time is up.
 
21 January 1977, Casa Grande (AZ) Dispatch, “KidStuff,” pg. 6, col. 1:
When do clocks die?
When their time is up.
 
19 January 1978, The Daily Tribune (Wisconsin Rapids, WI), “KidStuff,” pg. 12, col. 2:
When do clocks die?
When their time is up.
 
18 March 1980, Philadelphia (PA) Tribune, “Riddles,” pg. A9, col. 1:
When do clocks die?
When their time is up.
 
Google Books
1001 more cool jokes with Glen Singleton
By Glen Singleton
Victoria, Australia: Hinkler Book Distributors
2002
Pg. 141:
When do clocks die?
When their time’s up.
 
Google Books
Sensible Nonsense.. Frank’s Comic Pack:
Humour Pack Series
By Frank Paul
BookBaby
2014
Pg. ?:
When do clocks die?When their time is up.
   
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When do clocks die?
When their time is up.
#Joke from #TimeJokes in #Jokes,  #Humor and #Satire
9:42 PM - 21 Aug 2017