The sector plate had developed a slight warp, which was affecting how the tracks lined up vertically. As you can guess, to rebuild the whole thing would be complete nightmare, so a solution needed to be found.
Some sort of bracing would do it but what? Any sort of wood would be likely to assume the same curvature, in sympathy with the existing timber. However, metal, in the correct format, should avoid this happening. The answer was L shaped aluminium strip. The nearest B&Q to me has re-opened so off I went this morning and found just what I needed, a metre of 1.5cm x 1cm ally strip.
This was sawn to length and screwed securely down, as can be seen in the attached pic. It improved the situation but is not a complete cure. Some judicious rail height adjustment is still needed but much test running with an 08, with and without stock, has shown the way ahead. A Class 70 sailed over everything but being long and heavy it would...
The other pic shows the Scale Model Scenery 'wood' panel fencing in place, plus the test loco!
Thanks for looking.
steve