In fact, not only is it not illegal for you to maintain it, but it is also not illegal for you to sell equipment. Why? Because the patentee of this patent has exercised his rights when circulating the equipment, now he has no rights when the equipment comes to you. Let me give you an example. For example, Apple's iphone has a patent, and Zhang San bought one from a specialty store. Now the patent right is beyond Zhang San's control. Zhang San can fix it if he wants, and sell it if he wants.