Ok, then we have to check the output voltages. The easiest is to chek heaters. If everything is running high, then there might be a breakdown arc in the primary windings. I believe this is the common cause for failure. These trannys (the original 270BX) do not handle a high line voltage well. The primary inductance starts to collapse, resulting in temperatures to jump. This eventually leads to an insulation breakdown and short between windings. Total failure is when the arc jumps and primary draws too much current, blowing a fuse.
My original solution was to switch to the 370BX, which does not have the problem. In my newer products, I have successfully used the older Hammond style trannys by limiting the primary voltage to 115V. You wouldn't believe how much difference that little 5V can make. That, I believe, is the crux of the issue. I first did this on my CLARION, where I inserted lamps in series with the line to drop voltage. It worked great. On the CASTANET I use power resistors. Not only do they drop the voltage to reliable levels, but they also help to form a nice RC low pass filter, removing RF crap from the line.
jh