Hornby 2003 Princess Valve gear question, jumping crosshead

[mikesndbs]

Hi guys

 

Just been restoring this lovely loco but have become stuck with the movement of the crosshead one side.

 

It does not bind now but still makes an annoying pop as it runs.

 

Please have a look and offer your thoughts?

 

 

 

[Theakerr]

Check for clearances.  I have fixed a significant number where the piston rod connects with the front wheel nut.  If not fixed can do a real number requiring replacement.