Hello again. I read your feedback, and I appreciate your accepting the answer although it wasn't complete.
I did want to follow up since I owe you a little more information.
The reason I had not sent any information on a manual for that model is that I don't believe it exists in electronic form. The closest thing I could find, even from Memorex, was the MD6451R-BLK, which is the same model with a remote. It is listed under their discontinued products, and there are no active links from that page at all, including on the what should be the link for the manual. You can see that page here:
The next closest model number I could find a manual for is the MD6456. I honestly don't know how it's operation compares to yours, but I am assuming it would be similar, since it is in the MD645x series, and was available around the same time. That link will allow you to download the manual for free from a third party site.
Sorry I didn't come back and leave you that information earlier. But thank you for leaving positive feedback for me. I appreciate it.