Variegated or nutrient deficient?

[Ray]

Is it possible to distinguish N-, Fe- and Mg- deficiences on Paphs?

I don't think it's that simple. For one, different deficiencies can look similar. For another, a deficiency in one element can lead to a deficiency in another, making you treat the wrong thing...

 

[musa]

Thanks Ray, it's not what I hoped to hear, but I already guessed, that it is more complicated...
In that case I would do a total reset by repotting, eventually adjusting lights by the above mentioned test in partially shading a leaf and giving a balanced fertilizer. Is that reasonable?