After finding the ends of the exposed ribs were in poor condition we decided that the engine tray and water tanks had to come out. The engine tray is around 6 ft long and screwed to the engine bearers on both sides. After much levering with a screwdriver it finally came out. Underneath the tray lay years of mud and an oily scum about 3 inches deep.
When it was finally cleaned up we could see what the damage was, almost every rib and frame had seen better days so would need to be replaced, after the water tank was removed the support bearer was very loose and didn't take much to remove it. It too was very rot tern and again would need replacing.
The replacement ribs were planned up to size and fitted quite easy, the frames were a little bit harder to fit as they pass under two bearers but did fit eventually
While poking around in the engine bay the main engine bearer was soft in places and would need closer inspection, this is not something I wanted to replace if possible ( see the pic with the screw driver ) oh dear how wrong was I !!!.