XYTronic LF-1600 Soldering Station with H-E error

[riscy00]

After a long absence (1 year or more in storage), I turn it on and it now show H-E, which mean heater fault. It is not S-E which is electrode replacement. What do I need to check before buying replacement iron, I have tested two iron and both show H-E.

I open the unit and found no sign of burning or visual abnormality.

Suggestion what to check?