Yes that's right. Orange oil will do.
My friend used Pledge Wood Polish which contains orange oil. I tried my wife Strawberry oil from Body Shop, it works as well. WD40 also works, but I don't want my HE5-LE smells WD40.
Looks like any non-toxic, organic oil, can be used. Since the smell of the oil will stay on the HE5-LE for quite a long period, less smelly oil, or oil with pleasant scent is recommended.
The process is like scraping the sticky coating from the HE5-LE housing. Like removing stubborn sticker glue. Tissue cannot be used, it needs something stronger, a small towel is recommended.
It is better for the driver to be removed from the headband for easier handling.
It took me more than an hour to clean both both drivers. But it is rewarding to see my old, sticky, and dirty HE5-LE, reborn. It is now clean and shinny, and smells good
The cleaned surface and the sticky varnish coating.
Left surface is the cleaned surface.
After cleaning.
Before and after.
My reborn HE5-LE