You need to take the shell off the chassis and check that the smoke unit piston is moving up and down freely. You also need to take the smoke unit apart and check that the air hole in the smoke chamber is not clogged.

For the tenders, clean the track, wheels and rollers with naphtha to get any dirt off. Then disassemble the whistle motor and clean everything with the naphtha. Reassemble, and lightly oil the armature bearings.

Larry