Let's not get into legal arguments, I'm not a lawyer I'm glad to say...
The legal advice given to us is that a contract is between the parties directly involved, which is the person selling and the person buying. If the person who buys then sells it to a third party then he cannot pass on the contractual benefits that he had with the original seller. The new buyer then has rights because he has a contract with the person he bought it from, but he has no claim against the original seller.
I think you'll find that the same thing applies to the extended warranties provided with some new cars. The warranty may be for say 7 years, but the only person who can benefit from it is the original buyer, and as most people who buy new cars don't keep them for 7 years...
The standard of support provided by Lencarta to members of this website is exactly the same as that provided to all other customers - nobody gets better or worse service than anyone else.
What would Lencarta do? Each case has to be decided on its merits. If the item is under warranty and the customer bought from Lencarta then the item is either repaired or replaced. If it's out of warranty or if Lencarta didn't sell it to the present owner then it comes down to my discretion with small matters, and if I don't feel that I should provide a free repair or replacement then I refer it to the boss for a final decision. A couple of weeks ago a customer had a softbox rod break on a softbox that she bought about 5 years ago. That particular softbox is long discontinued and there are no parts available for it so she was given a brand new softbox of similar type, and she was delighted. If a softbox rod had been available then she would have been given this instead, even though the warranty was long gone. This free replacement was possible simply because there was something suitable available, and like most reputable Companies Lencarta will always do what it can to help, even when there is no contractual liability.
Most repairs/replacement parts don't cost very much and it's often a good idea just to put things right for free, but as I say there are limits.
I'm not saying that Lencarta's attitude towards customer service is any better or worse than anyone else's - what I am saying is that people shouldn't assume that the manufacturer/original seller will necessarily honour a warranty that belongs to someone else. Which comes back to the original point - buying from Ebay-only sellers is also risky, because they don't have repair facilities, don't usually know anything much about the stuff they sell and may not be too worried about their customers, once the time period for leaving negative feedback is concerned. And the same comments may apply to some of the non-ebay online sellers too. Even if they are well intentioned, they may not be able to provide proper customer support and will probably not even still be dealing with the factory that made the gear by the time it breaks, because they change suppliers frequently, buying on price alone.
And of course, they may not even be in business by the time it goes wrong...