Suzuki DT25 - Recoil Strarter Problem

[gsk2005uk]

I have a 2-stroke Suzuki DT25 (Model No:02503-132880) and I am no longer able to start the engine manually via the rope/recoil starter. The recoil starter seems to operate as it should, ie twist and automatically pulls the rope back in, but the engine is not starting. I am only able to start the engine using the normal way, ie connect a battery and press the ON switch.

Does anyone know how to fix the manual system?

Thank you in advance