I've just fired off an e-mail to whom I bought the engine with some pics and I'll see what will happen.

I probably should have just pulled the engine and sent it back but I live in Australia and I bought it overseas. Now I've stripped the motor I don't really expect any support, a new rear bearing posted free of charge would be the best I could hope for as I certainly won't be posting them a box full of motor bits. Given how well the engine is sealed up I'm surprised how the oil manages to work itself around to all the bits...