I have been contructing part of the valve gear, as shown.
The detail of this kit is such that the combination lever, with a complex shape at its top, if faithfully reproduced. Unfortunately this means that the where the lever goes through the crosshead of the piston valve (see the diagram at the top for the names of these tiny bits of brass!) it is such a tight fit that there is not enough movement in the model form.
These are pictures of the piston valve shaft and crosshead (all one moulding) and the combination lever. Unmodified as yet.
They both have to be carefully filed back to allow the combi. lever to move through an angle of about 25 degree either side of verticle in the crosshead.
Click to see progress.