I have an electric reclining sofa from DFS (UK). It works perfectly well, but the transformer sporadically emits a constant buzzing noise. I have found that a gentle slap cures the problem – but eventually the noise returns again.
I presume the transformer core used in the transformer is made up of E & I combination of laminates.
1. Get some tools and tighten all the screws that holds the core laminates together. The buzzing sound signify the core laminates are loose and are vibrating.
2. it is also possible to coat or revarnish the transformer core with some clear lacquer varnish.
I would agree with what the guest has said above. it is either the screws loose or the laminating going off. try to do the above and keep us informed if it solved your problem.