[Alan Anderson]

We just hooked up our new 884s on our "official" testbed 'bot today. They weren't getting a PWM signal, just sitting there flashing orange. We spent a while making sure the RC was putting out signals correctly, using a servo to verify that the outputs were doing what we expected.

I finally noticed that one of the PWM cables was plugged in backwards, and in the process of correcting that I discovered that none of them had been inserted far enough. They went in with a very firm "click". Now they work fine.

Though you say they're in far enough, your symptoms are consistent with the PWM cables not being solidly connected. Try applying just a little more force than you think you need to when you plug them in.