You have fully recovered hundreds of heads? Can you provide any proof of this. And a link to your business as this sounds very dubious? I have never heard of a business specialising in repairing solvent heads. I'm sure if this was true you would be very well known in the print community?
My 'hate' as you put it is for chinese sellers selling non working parts, or cheap copies of OEM parts like dampers, captops etc.. that don't work as well as the original parts. Not sure why the mods would need this bought to their attention as it is a view held by most printer technicians.
The parts I sell are tested ON the printer. If a scan motor works on the printer when running test prints without throwing up any error codes, then it is good. The same as with boards etc... Oddly out of all the parts I have sold over the years, I have had zero returns for non working parts. I don't need to justify my business to you, but I get parts from fully working and tested printers for parts.
As for 'People on this forum have stopped commenting and helping others, because of you' provide proof? Have you spoken to every member on this forum?
I don't know what your story is my friend.
But it may be true that the original parts are better tested or are of 10/10 quality, but sometimes and mainly in underdeveloped countries, these cost a lot of money.
That's why you end up resorting to pieces from another origin that may be 8/10 but they work. If the heads cost $100, no one would clean them or try to save, they only do it because the cost is great and that is why the Chinese teams triumphed and if you look, they increasingly use cheaper and disposable heads.
On the other hand, the heads in good electrical condition are repairable because, as I already said, the problem is that the external layer with the micro-holes separates from the internal one and loses tightness, thus creating a pressure that is not capable of being moved by the pizoelectric actuator of the nozzle
