Not very much thread drift, but I was on an AA 767 returning from .... somewhere (?) a few years back, when my seat arm did something very similar. There was no-one in the seat next to me and I wanted to spread out a bit. I lifted the seat arm, but when it got to about 45 degrees all the cabin lights went out and there was a distinct smell of 'train set'.
I returned to seat arm to home position and after a few seconds the lights came on. I thought; 'that wasn't me - was it?' I had more or less convinced myself that it wasn't, so I tried again. Wham - out went all the lights and the smell of burning came again so, I returned it to level very quickly. As an engineer, I wasn't about to challenge the power supplies on my aeroplane if I could avoid it so, as soon as I could, I collared one of the crew and warned him seat arm 28F was the cause of the cabin lighting failure. He was very polite, but totally condescending - how could an SLF possibly know about aeroplane problems?
When I left the aircraft at LHR, I reminded the CC that seat 28F had a serious problem and they smiled sweetly and said they would look in to it.
I bet that 767 took off again with a serious electrical problem.
Roger.