Cannot recall the detail now, but it was from a BA trainer on a sim check who was adamant that if you close No 2 with alt flap at less than 15, alt flap switch 'OFF', flap lever 'UP', the LEDs will retract on the PTU. I cannot remember the detail now - it was many years ago. I never tried it. Something for spare time in the sim? I can't remember why you had to close No2 - I would have thought the PTU would have worked anyway in that config.