Precisely what I thought, Mileage has been done since April last year when the bike was bought brand new, although the bike is Chinese the chain is a Japanese RK chain £199.00 ( new ) as fitted to many Honda's, Suzuki's and Kawasaki's. The chain has to have let water in or the links could not have seized, it probably happened on the Ride to The wall when it was in the rain all day long from 7:00AM to 10:00PM, it still of course should not let water in. The cause could be poor chain assembly then! If they don't press the outer plates far enough down then as you know the seal will be broken, but it's still going to be difficult to get some oil back inside. It's not going to be a case of the life of the lubricant in the chain going off in less than 12 months, which I thought might have been a cause - if the chain had been on a long time.