Bad recordings from RCD-W500c

My church records our weekly services on a Sony (RCD-W500c )CD burner. At times the CD appears to record and finalize properly, but when I try to play or copy the disc it won’t play and my PC doesn’t “see” anything on the disc. When I look at the CD I can see see that it WAS written on. I called Sony, but the tech support person wasn’t very helpful - suggesting that we change the type of CD-R audio disc and that we disconnect / reconnect power to the recorder. (He also said NOT to use a cleaner disc because the brush could scratch the lens) Neither of these has fixed the problem. Do you have any suggestions for fixing this problem? Is there any way to retrieve the audio from the bad discs?

This drive is VERY old.
I would buy a newer one, maybe even from ebay.
Yamaha & Plextor drives are great.