All issues of whether the styrene might wear over time aside, even with added weight on the trailing truck, the chassis still wouldn’t go around a 6ft curve reliably so more drastic measures were needed.

Using a piercing saw I cut out part of the inner frames.

Then I soldered a plate across the ends of the frames at the front by good fortune there were two tabs at the rear with could be soldered to.

I then reduced the width of the inner plate and soldered the frame pieces back together with some end plates to take up the gap left by the saw kerf.

A quick dry fit of the rear truck leaves plenty of space either side of the inner swing so there should be no shorting but I may need to remove some of the spring casting to allow more swing to help it get around the curve – it’s a long chassis.