Bonjour,
I also contacted Jin for a problem with a faulty CDI module and he immediately offered to send me a new one.
I also had problems with my M91 but a friend helped me to repair it.
China is far from France, a very small market for them and I regret that there is no more in-depth quality control before sending to the whole world.
I also had the same kind of problem with my Enjomor MK3 purchased from Stirlingkit and again, we repaired the engine ourselves.