Fly press backlash

[Thrashsmith]

I bought a FJ Edwards No.8 fly press the other day which has quite a bit of backlash in it which I'd like to correct.
The top nut is the split collar and the bottom nut is the lock nut. I can get a little bit of movement into the split collar but only the tiniest amount of movement into the lock nut.
The lock nut is also a little recessed into the top of the ram, so I'm generally a little stumped for how to loosen it up.
I found a great little video on YouTube by a fella who restores them explaining that the top nut is the cast split collar and folks often break them thinking that they need to swing on that one to undo things when it's actually the bottom nut that you need to undo.
Does anyone else own a fly press by this manufacturer? Is your lock nut also recessed? Anyone with any pearls of wisdom as to how I can undo the lock nut?
I have posted pics below, then a link to a video I uploaded to YouTube, then the video I found of the guy who does the tutorial. Any help would be appreciated.
Cheers



My video...

Tutorial video...

 

[Agroshield]

Did you notice in the video when he cracks the locknut which direction he moved it? It was anticlockwise looking down from the top, which for a RH thread would move it upwards. Before he even starts, there is a gap between his split nut and the locknut, which is different to your arrangement.

I do not think heat will hurt your one. Build a dam around it with plasticine or silicon. Fill with diesel and leave for a week. Empty out and then warm and try again. If not, fill and rinse with solvent until all grease is gone and repeat soaking with vinegar (or Erustovap).

Perhaps try to make your spanner a little tighter and fully enclosing all six sides (you will have to weld it insitu for this).

This is speculation but perhaps the split nut has been screwed in way too much so that it has bottomed out in the bottom of its threaded hole. Perhaps this is what is holding the screw to the ram rather than any contribution of the locknut. This would also explain how it still works without falling to bits with the locknut up tight to the top. Try tightening the locknut and see how far down it goes. Try just loosening the split nut.

When you reasssemble, you maybe need a thick washer under the locknut so you can access it when it is tight.

In non-backlash operation, I am gussing that the end of the screw bears against the ram as you probably do not want the screw pushing on the split nut. In order to remove the backlash, you will need a thrust spacer inside the ram.

 

[Thrashsmith]

Wouldn't it be great if the manufacturers had just come to a consensus on the small details and just stuck to it across the board...