I recently acquired a 1956 Royal Quiet De Luxe with a backspace problem.  The backspace happens but does not maintain the new position after releasing the backspace key.  What should I be looking for?  I have the back panel off trying to determine if the linkage was off, but I don't see anything obvious.    I did notice that if I lift the left corner of the carriage it will work okay.  Has the position of the carriage or carriage rails shifted and is perhaps causing the problem?