Faulty Trelawny scabbler .

[LKSF]

Does anyone have any knowledge on repairing these to pass on?
I picked this up cheap:

and it doesn't work, the piston is loose, just won't vibrate in and out.
I don't think i'm short of air, (towable diesel compressor), exploded parts diagram here:

https://trelawny.wpenginepowered.com/wp-content/uploads/2022/10/735.5300-SF-Scaling-Hammers-SH-Scabblers-14.06.2022-UKCA.pdf

I've had it apart, everything looks ok, all loose and sliding, but have no idea what i'm looking at or for really. The only thing which I can see which is, or could be worn is the seal No.22

 

[Mick-the-fitter]

I would check all the parts against the parts diagram, But definitely 18 the spring and 33 the valve!