That sucks. I wonder why they don't mention the adjustment dial on the top in the manual.
From the manual :
"To change the delay after motion is detected before an OFF code is transmitted:
Press the House/On button once. The red light flashes. Then, (within 3 seconds) press and hold the Unit/Off
button. The green light turns on. 3 seconds later the red light reports its delay setting as follows:
1 blink for Analog setting, i.e. the setting on the dial on the top of the unit...... "
X10's manuals make you do heavy reading between the lines.