When I wound up with the 561 from my dad's company, 30 years ago, it had a replacement filament transformer. I discovered that, in fact, the problem was a breakdown in the filament winding, not a problem in the original power transformer. I slipped some shrink tubing over the offending wire and used the 'scope, without the flying transformer, for many years. Right now it is, sadly, sitting without its HV transformer. It had a hard failure and was immune to baking. I've wound a new one but have not gotten around to potting it, 50-50 paraffin/bees wax. Someday.
