I am not familiar with your kind of machine,
I know you cleaned it but something couldn't be jammed somewhere could it, a rogue pin or clump of thread? Or maybe the power is not fully plugged in at either end. I had a similar thing happen with one of my machines and I had been winding bobbins and forgotten to disengage the bobbin winder function properly. It was kind of stuck half way.
Hope your problem is resolved and all goes well with your eye check.