Struggling with Oncidium — would appreciate advice

I want to be honest: I'm not getting great results with Oncidium and I'm not entirely sure why. scale insects on pseudobulbs and undersides of leaves has been a recurring problem despite my attempts to address it. I've been focusing on feeding with a half-strength orchid fertiliser weekly in summer based on everything I've read.

extraordinary bloom longevity lasting weeks to months is there in glimpses, which tells me the plant has potential in my conditions. I have it in a north or east-facing windowsill which might not be ideal. rest period in summer with focus on leaf and root growth showed some improvement. Two stars for now — not the plant's fault, but not a success yet. I'll update if things improve.