Plarail Percy/Thomas Spring Lock problem

There should be a spring on the part that is hanging down. The spring keeps it pushed up against the bottom of the chassis, and in this position it stops the locating tabs on the body shell being squeezed inward so the shell can't be removed.



To remove the body shell you have to push the sprung part down, against the spring, so that it clears the tabs. Now they can be squeezed inward and the shell removed.



Remove the plate on the underside of the chassis that retains the non-driven axle and the sprung part.



You can now remove the sprung part, which should have the spring on it like this.



It goes back in like this, with the arm of the spring pointing towards the front of the chassis.