Help needed for my AA S410 power regulation/servicing

[Shoot4Toffee]

My S410 chrono'd at 9.4 ft/lb, with 180 BAR and dropped to 6ft/lb at 150 BAR. I have stripped the bolt action, and triger housing, removed a compacted bit of dusty grease from the action, fitted an "O" ring into the transfer port (to the barrel) and the thing now chrono's at 4.5 ft/lb at180 BAR! I guess the next step is to check the air valve for obstruction, and the regulator behind the anti-tamper access.

Expert opinion and instruction on the above would be appreciated, PM me if your information is not for general consumption, I want to bring the power up to legal limit, I have an assortment of bolt springs, but as the loss of power is so great, other problems need to be eliminated.

Thanks, Tom.

Before sending it for service, I want to learn all I can about the mechanism.