About Lite-On DVD/HDD Recorder?

Question

i have a Lite-On HD-A740GX DVD/HDD Recorder and the problem i have is the DVD/CD Rewritable Drive is not copying from HDD to Disc. i have search for this model of rewritable drive and cant find anything regarding replacing the drive. Can anyone help me in finding an exact replacemt for the drive (model LMU-713H) or a suitable replacement that will work in conjunction with this model.