I totally understand the other users anger when being offered (paid) products and services in response to a question for help/advice on a forum. I'm afraid it's not a question of ethical. Doctorman, as helpful as some may feel it to be, is not allowed to be trading or selling on this forum.The offer to sell parts isn't unethical; in fact it's helpful to those that can't afford/don't want to replace their head units. Taking advantage of the situation would've meant Doctorman kept his mouth shut and simply sold new units to those oblivious to upgrading hardware.
I was advised by some, to read the rules when I inquired about using languages other than English in post. I did, and subsequently read that selling and trading is prohibited. We can't have one rule for one, and not the other can we? Let's have it right!