Use a signal enhancer. If it is a standalone combo unit, you will have to run it from another vcr, to the signal enhancer, to the recorder. There is most likely no way to bypass the internal copy protection on a stand alone. Old, worn or low quality tapes have been know to accidentally trigger the copy protection with some devices.
Here are some threads that may contain info on signal enhancers.
Search sima to find more threads (sima's may be hard to find but it often gets mentioned so its a good search term when looking for info on other enhancers).