Hi, after taking the gearbox to a specialist, I was told an internal casing for the gearbox had cracked which meant the clutch had fried and the chain had moved out of position also. According to the specialist, too much damage done.
Following this event the gearbox specialist pointed out an the gearbox on eBay I should purchase. The most painful part about this is that after fitting this second hand gearbox £500 to fit this also proved that the clutch was slipping on it as well. Although I have done approximately 15,000 miles on this second hand clutch, the problem is when I am on a uphill and moving from idle position it jerkrs very badly or sometimes it doesn't make it. Living in a valley doesn't really help. The point I'm making here is if you are going to purchase a second-hand gearbox make sure you get it tested which can be difficult if it's not mounted on a car. The way to test the clutch is on a incline make sure it doesn't jerk when going up.
Hope this helps.