Here is the code in my Marlin...

Code:
#ifdef ULTIPANEL_FEEDMULTIPLY    // Dead zone at 100% feedrate
    if ((feedmultiply < 100 && (feedmultiply + int(encoderPosition)) > 100) ||
            (feedmultiply > 100 && (feedmultiply + int(encoderPosition)) < 100))
    {
        encoderPosition = 0;
        feedmultiply = 100;
    }


    if (feedmultiply == 100 && int(encoderPosition) > ENCODER_FEEDRATE_DEADZONE)
    {
        feedmultiply += int(encoderPosition) - ENCODER_FEEDRATE_DEADZONE;
        encoderPosition = 0;
    }
    else if (feedmultiply == 100 && int(encoderPosition) < -ENCODER_FEEDRATE_DEADZONE)
    {
        feedmultiply += int(encoderPosition) + ENCODER_FEEDRATE_DEADZONE;
        encoderPosition = 0;
    }
    else if (feedmultiply != 100)
    {
        feedmultiply += int(encoderPosition);
        encoderPosition = 0;
    }
#endif//ULTIPANEL_FEEDMULTIPLY
Change it to this?

Code:
#ifdef ULTIPANEL_FEEDMULTIPLY
// Dead zone at 100% feedrate
if ((extrudemultiply < 100 && (extrudemultiply + int(encoderPosition)) > 100) ||
(extrudemultiply > 100 && (extrudemultiply + int(encoderPosition)) < 100))
{
encoderPosition = 0;
extrudemultiply = 100;
}


if (extrudemultiply == 100 && int(encoderPosition) > ENCODER_FEEDRATE_DEADZONE)
{
extrudemultiply += int(encoderPosition) - ENCODER_FEEDRATE_DEADZONE;
encoderPosition = 0;
}
else if (extrudemultiply == 100 && int(encoderPosition) < -ENCODER_FEEDRATE_DEADZONE)
{
extrudemultiply += int(encoderPosition) + ENCODER_FEEDRATE_DEADZONE;
encoderPosition = 0;
}
else if (extrudemultiply != 100)
{
extrudemultiply += int(encoderPosition);
encoderPosition = 0;
}
#endif//ULTIPANEL_FEEDMULTIPLY