Hmm... That last comment about the dimmer setting (I assume you mean the standard dimmer, not the LED brightness) is rather curious. This implies (to me) that the fault is also causing problems with the standard VFD. Look along the power lines feeding the resistor pack.

Either that, or the fault may be with the display board itself, and not the LED circuitry. If there were a bad capacitor (or other component) you would see symptoms in the LEDs and VFD, but they would not be the cause.

In any case, I strongly suspect a power lead. On Brian's original button page, the knob is connected to the +5 of the IR board and ground near the knob. Different power leads... And your symptoms seem to support this.