I was not sayin you got the wrong timer, I just wanted know if your system controls were 120v or a low voltage set up, because the site I found to build your own Ebb system controls when I was researching ebb n flow had very reasonable prices on DIY kits ,I think like $115.00 US for the whole complete package , and they sell individual parts the timer they sell looks like the timer you show in the picture but at a much lower cost. I was giving you a web site for future replacement parts at a much lower cost.
As far as the replacement of your new timer , Yes simple to do ,the whole control system is a very basic in series wiring straight forward design that I am sure you will not have any issues replacing any part in the ebb control system.
Now if you wanted to fix your old time ,it is most likely just hung up , most likely if you took it a part you will find a small gear reduction motor that either the gearing got hung up or the small motor it self fried , you can OHM the motor ,if its good realighn the gearing and grease . these are very similar to Defrost timers that you find in frezzers or refrigeration.