I brought a 2002 Terios with a knackered gear box off a mate I found another gear box from a 2000 model but when I recieved it I noticed the bell housings are different. I thought no problem I'll just use the bell housing off of my old gearbox on the new one but when I tried to split the bell housing from the old gear box all the gears tried to come out with it and it wouldn't come off. Is this because the box is knackered or am I doing something wrong?