Understood Pete.
But this time around on this new Ten Wheeler (at least mine) there are not the usual "nibs" to prevent rotation of the roller.
So the double engine roller in question has nothing to hold it to the chassis but the one small screw. The screw sits at the one end of the double roller with nothing to prevent pivot at the other end. The smooth surfaces and one screw cannot prevent this large double roller from moving side to side.
Dave