danb

Those chargers corrode fast especially if they are not kept clean and dry wiping them with each use.

Even with brand new, never been used batteries I've had to lift the center pin to make a solid connection with the charger. Let us know how you fare.   

It's been a while since I've charged one too, but I just plugged in one of my old back-up eGo batteries and it stayed red until charged, then blinked red/green a few times, before going to solid green, indicating full charge.
If memory serves,  a slow-blinking red means the battery is not making good contact with the charger or the battery is incapable of charging (defective).  Try lifting the center pin of the battery by prying it up, slightly, with a small screwdriver and that may solve your problem.  It could just be the battery is beyond it's life-cycle and won't charge again?
Have you also tried a different charger?

It has been a while since I charged an eGo style battery. Thinking back, the last ones I charged did the same thing. It is normal, but if it makes you nervous, don't leave it unattended while charging.