As far as I can tell the only time any text would display is if you are in the Measurement mode, and it'll show the time, or voltage, between two cursors. Are you sure they aren't visible in Measurement mode, maybe they have been moved off-screen (if that's possible)? do the indicator lamps around the Cursor/Measurement area work?
This is something that could prove difficult to troubleshoot, however it's not critical for the functionality of the oscilloscope. It's a handy way to measure time and voltage, but you can always do that by looking at the graticule and your scope settings as well, it's just less convenient.