I have a combo

Question

I have a combo dvd vcr player model #DRC8335. I am at my wit's end, the first one I had I returned because of a clock problem...now this....when I tape a dvd disc or play a prerecorded one, I do not get any audio, just the visual. I CHECKED the connections....seem to be o.k. what should I specifically look for to remedy this....Help Me!!