I discovered these while messing around with my watch... It helps to press Adjust before the other buttons, so you don't switch modes instead of going into the test modes... Press Adjust, Mode, and Time Memo simultaneously: display shows TLT, this tests the tilt sensor used for Auto EL. Display shows "8888" when sensor is triggered. Press Adjust, Time Memo and Receive simultaneously: display shows SLR. Not sure what this is, I guess it's testing the solar cells or something. Display shows 8888 but it doesn't seem to change when I expose the watch to light or darkness. Press Adjust, Mode, and Receive simultaneously: all display segments light up. Press Receive, half the segments extinguish. Press Receive again, watch shows some numbers that could be a firmware version. Mine shows "2609 U -1". Press Mode, Receive, and Time Memo simultaneously: Display shows 60 U. Receive toggles between 60 U/60 J/40 J (the 3 atomic bands), and Time Memo attempts a receive (perhaps for testing what bands you can receive).