to correct for misalignement with the 5v steppers, make the following modifications to the firmware...

to EggDuino.ino - add just before definition of setup()
(or uncomment these lines if they already exist as they did in mine):

float rotScale = (float)rotStepsPerRev / 3200.0;
float penScale = (float)penStepsUseable / 800.0;

in Helper_Functions.ino - replace #ifdef block with this:

#ifdef BOARD_ULN2003
        // map 3200x800 eggbot corrdinates to our 28BYJ-48's penStepsPerRev and rotStepsUseable

/*
 * original
        rotStepsEBB = map(rotStepsEBB, 0, 3200, 0, penStepsPerRev);
        penStepsEBB = map(penStepsEBB, 0, 800, 0, rotStepsUseable);
*/

    long rotStepsX16 = (long)(rotStepsEBB * 16L);
    long penStepsX16 = (long)(penStepsEBB * 16L);

    // Compare regular solution against 16x magnified solution
    long rotSteps = (long)((rotStepsEBB) * rotScale) + (rotStepError / 16);
    long penSteps = (long)((penStepsEBB) * penScale) + (penStepError / 16);

    rotStepsX16 = (long)((rotStepsX16 * rotScale) + rotStepError);
    penStepsX16 = (long)((penStepsX16 * penScale) + penStepError);

    // Compute new error terms
    rotStepError = rotStepsX16 - (rotSteps * 16L);
    penStepError = penStepsX16 - (penSteps * 16L);

    rotStepsEBB = rotSteps;
    penStepsEBB = penSteps;

#endif