You will find all of the replacement parts you need on this page
http://www.rainbird.com/shoppingv5/shopdisplayproducts.asp?id=590&cat=ESP%2DTM
Transformer: Plug-In Transformer for all ESP-TM controllers.
Plug in Class 2 transformer
Model: AC2650650
Input: 120V AC, 60Hz, 24W
Output: 26.5V AC, 650mA
Fourth item down on the page. Hope this helps.
Tony Posey
Ridge Run Landscapes