yeah I saw those when I purchased the cables and took them off before I used them. It looks like I will be making the drive to Syracuse to get it fixed.
How to you know the problem is with the receiver? In my view it is more likely to be the CD player.
Before sending the receiver in you need to connect something else to that receiver optical input.
Also, I have not used Monster cables for years. Their cables are not of good build quality and they would be the last cables I would use for lots of reasons.
The other issue is that all optical cables are very fragile. If you have a tight turn behind your receiver (common) you can destroy an optical cable in a hurry.
So before going to Syrcacuse, connect another device to the receiver on that input. If it does not work, get a different cable and handle it very gently. Fiber cables are made of glass. As you know glass is fragile.