Fitted a new probe O-ring. No better.
Worse still when I tried to fill it up it began leaking air at around 150 Barg. Appears to be coming from a point where barrel meets the action. Loses pressure quite quickly.

Thought I would take it to Customguns at Hartlepool. However it would appear that he stopped accepting work in September. Showing "permanently closed" on internet.

Anyone any further thoughts or is it a hefty bill coming my way.

Thanks
Al.