T-104 has 240Volt clock motor
WH-40 water heater timer has same 240Volt clock motor
T-103 has 120Volt clock motor
T-101 has 120Volt clock motor
T-100 series 120Volt and 240Volt clock motors sell at Grainger for $16
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hiSee large image of clock motor on back of Intermatic timer
http://waterheatertimer.org/images/Back-of-T-104-800.jpgTo replace clock motor you need 6-sided star-screwdriver from auto parts store or hardware
You may also need tweezers or magnetic screwdriver if tiny screws fall down behind timer when replacing
Steps:
Order 120 or 240 volt clock motor
Turn off power to timer
Remove plastic cover over screw terminals
Take photo of wiring or make a drawing
Note exactly which terminals the clock wires connect to
Clock motor wires can connect to either terminal, there is not a plus or minus wire to clock
Loosen screws on front of timer to remove white-colored clock motor wires
Push the spring retainer located inside box at top ... this will release timer mechanism from box
Tip timer out and then lift up to release timer
Replace clock motor that is held by 2 screws
Keep clock wires away from other timer parts on back of timer
Snap timer back into box
Re-attach wires to terminals just like they were before
Tighten screws very tight against copper wires
Turn on power
Check that dial is rotating as time passes
See more
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html