How can I fix my DVD/VHS Combi BUSH DVHRS02?

When I record a R/W disc and play it back, the picture fragments and freezes around 1 hour to 1.5 hours from the start and won't go any further. When playing a shop bought DVD movie, it plays OK right to the end. Does the same laser lens record and playback ? I've played the discs on another recorder and they still break up and freeze around the same time. I assumed the digital recording part is faulty. Is there anything I can do.? The Combi has worked fine for two years from new, until now.