Horstmann timer stopped

My central heater timer has stopped - it's a Horstman 425T Tiara. I can still manually turn the boiler on or off using the 'all day' and '24 hrs' controls but the clock won't turn.

Are these things repairable or is it more likely I'm going to have to get a new one? If it is repairable is it a professional-only job?

Cheers

Cheaper and less time consuming to change the timer. You will get one that fits straight onto the back plate possibly without any wiring alterations.