An engineer can be summoned, I've seen it happen and been the cause of it once, and may well be on board anyway, if you check your bed before getting settled on boarding. It's not frowned upon by cabin crew, in fact anyone in CW really should do this before take off, it takes 10 seconds. It does need to be moved back to the take off position before departure. It may be more expedient to move you to another seat, or shift a staff member on concessions, but it's better doing that before departure than when lights are out and it becomes difficult to fix without disturbing everyone around you. Most of the CW seats are plumbed into your neighbours' seats.