I have intermatic timer T30003R. How do I change the timer motor

You have the T103 timer rated 120-240. The clock motor part of timer is 120Volt. This is a very versatile timer, but confusing for non-electrician and electrician alike.
Solve problem by converting timer from T103 to the 240V T104 by changing clock motor from 120V WG1570 to 240V WG1573.
Buy wg1573 clock motor at WW Grainger or drillspot etc.
Resources:
http://waterheatertimer.org/How-to-replace-Intermatic-clock-motor.html
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T104
This simple fix is intentionally designed by Intermatic so their timers are not only adaptable to all electrical needs, but also can be maintained to last 25 years by replacing clock motors and trippers as needed

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Yes. Change clock motor from WG1570 to WG1573
Wiring is same as T102 timer:
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T102
http://waterheatertimer.org/How-to-replace-Intermatic-clock-motor.html

2) If new pump motor is 2-speed, then converted T101P3 cannot handle 2-speed pump.
Use T106 timer, or T1906 timer:
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#2-speed
http://waterheatertimer.org/How-to-wire-T1906-Intermatic-timer.html#pool

3) New T106 or T1906 timer mechanism will snap into T103P enclosure without changing boxes.
Any intermatic timer will snap into Intermatic enclosure.
Other brands of timer can adapt to Intermatic enclosure using Tork IAP adapter bracket.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Copy fo0llowing links:
http://waterheatertimer.org/How-to-replace-Intermatic-clock-motor.html#clock
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#Hz

2) The suffix, -1 and -3 are not important.

3) WG733 is 208-277 Volt clock motor, normally found on sprinkler timer or T1900 series. WG430 is 120Volt clock motor normally found on T1400 series.

4) T103 timer is stock 120Volts, but can be changed into different voltage timer by changing clock motor.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Intermatic T174 wires exactly like the T104 240Volt timer.
Only difference between T174 ans T104 is the day skipper wheel on T174.
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T104

These timers are very versatile and can be wired many ways, and changed to control different voltages by changing clock motor wires, or changing clock motor.
Voltages include typical 240Volt. But also 277V, 480V, 120V, 208V and 24Volt

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

T104 timer is 240Volts.
Not 120Volt
You can convert timer into 120V by changing clock motor from WG1573 to WG1570. This action will convert the T104 into T103.
http://waterheatertimer.org/How-to-replace-Intermatic-clock-motor.html

The T104 timer can be wired many different ways:
Copy following link for illustrations showing both T104 and T103 wiring
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html

Add a comment with specifically what you are connecting to timer, and I will comment back with more detail as needed.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for T103 timer wiring options:
The clock motor is 120Volts, but clock motor can be changed from WH1570 to WG1573, and this action changes 120V T103 into 208-277V T104 timer:
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T103

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Timer is repairable. Override lever is not replaceable part.
The timer dial is moved by the 240Volt WG1573 clock motor
Buy clock motor. And buy new trippers.
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html
http://www.grainger.com/Grainger/INTERMATIC-Time-Clock-Motor-1PNK2?Pid=search
http://www.grainger.com/Grainger/INTERMATIC-Timer-Tripper-2E054?cm_sp=IO-_-IDP-_-BTM_BTB05209020&cm_vc=IDPBBZ2

Thank you for including model number.
Intermatic catelog shows that T40404R is shipped with two T104M timer mechanisms.
However the mechanisms can be changed out for either T101M or T104M, and these timers can be wired many different ways so there is not 100% certainty unless you know or test voltages.

Here's the general difference
T101M is 120 Volt with 120Volt clock motor
T104M is 240 Volt with 240Volt clock motor

You can buy $20 clock motor and $3 trippers and fix the timer mechanism instead of replacing it.
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#T100
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html

Add a comment to this thread any time as you're working on project and I will get message.

Other useful links:
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#pool
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html

Upvote the help.
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.

Yes, the T101M 120Volt pool timer requires both ON and OFF trippers:

Grainger sells T100 series on-off trippers:
http://www.grainger.com/Grainger/INTERMATIC-Timer-Tripper-2E054?Pid=search
Amazon sells T100 trippers
http://www.amazon.com/dp/B003YO2C5U/?tag=picc-20

Grainger sells the T100 125V clock motor
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hi

How to wire T-101 120Volt timer
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T101

How Intermatic dial timer clock works.
Clock motor rotates dial.
Intermatic clock motor, located on back of mechanism, are replaceable
Trippers located on outer edge of dial push on-off lever
ON tripper pushes lever one direction
OFF tripper pushes lever opposite direction.
Lever pushes electrical contacts together and pulls contacts apart.
When lever moves, manual override also clicks back and forth with audible click.
To replace timer, replacement snaps into box without needing to changing box.

You can replace clock motor on many Intermatic timers:
Snap mechanism loose using metal spring top inside box.
Tip mechanism out and get clock motor number off motor.
Google search specific clock motor number.

Aplus sells many clock motor:
http://www.aplussupply.com/intermatic/timermotors.htm
Electric supply online sells clock motors
http://www.electricsupplyonline.com/prod/intermatic-motors.php

Grainger carries inexpensive clock motors for T101, T103, T104 timers.
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hi
T101 and T103 use 125v motor
http://www.grainger.com/Grainger/INTERMATIC-Time-Clock-Motor-1PNK1?Pid=search
T104 uses 240v motor
http://www.grainger.com/Grainger/INTERMATIC-Time-Clock-Motor-1PNK2?Pid=search