Sounds like a loose connection in the timer if it turns off or on when you wiggle the wires. Depends on how the wires are connected inside the timer whether it'll be a straightforward or difficult thing to fix. May or may not require soldering skills. Might just be that the wires are held into place with screws inside the timer, in which case it'd be easier to fix I think.
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local