As far as is known units produced between July 2015 and September 2016 might be affected, which have one of the following serial numbers:
B57, B58, B59, B5A, B5B, B5C, B61, B62, B63, B64, B65, B66, B67, B68, B69.
With the wrong installed cooling fans, warm air from the final stage of the TS-590SG flows to the display electronics, instead of cold air from the ventilation holes in the bottom plate to the final stage. If your TS-590SG is affected, you should contact your dealer and ask him for advice.
My TS-590 has serial number B5A10100 so it should be affected as well. This is what I saw after removing radio cover.
After removed all screws and part of the panel, it looked like this:
Removed fist 4 screws from the first fan and put it to the right direction.
It should look like this, when both fans are installed correctly.
Gray cover plate is also back and now can put black cover back to the right place.
Radio is assembled and will be tested on the weekend in a contest.