To be honest I'm not 100% sure on this one as I have never run into such a problem.
Unless you have a volt/ohm meter to check the timer you may just need to replace it to see. Sometimes you can look at the connection on the back of the timer and see burnt spots on the timer body were the wires plug into it.
That is often a good visual sign that the time is the problem or soon will be.
If you do decide to replace the timer place keep us updated at to if it corrects the problem or not.