There is a hardware bug that may occur on the replica 1 boards. It causes occasional dropped characters from the display. There is a fairly easy fix but it does require soldering.
Requirements: .01uF ceramic disc capacitor, soldering iron (25W preferred) and solder.
Locate the chip labeled 74LS04 on the circuit board. Pin 3 is on the side that is closer to the edge of the board. Pin 14 is on the other side of the chip top pin. So, the pins are labeled as follows:
|(74LS00 is here on the board)
|----- this is the edge of the board
|----------- 6821 is here on the board
Pin 1 and 14 are closer to the 6821. Connect the ceramic capacitor on the bottom of the board to pins 3 and 14. Make sure the capacitor doesn't touch any of the other pins on the chip. This will eliminate all dropped characters.