I've had one leak from the area between the top of the grip frame and the bottom of the body. There is a large oval shaped o-ring that seals the "macro-less" air passage from the grip frame to the body. The ONLY way to service it is to remove the frame.
Take the grips off and then grab your hex key and take out the rear frame bolt, and then the front (this one is captive). Gently separate the two parts and you'll the the o-ring. Make sure its resting in the proper position, give it a
light coat of lube, and re-assemble. The key here is not NOT disturb the o-ring while you're reattaching the grip frame.
Start my lightly tightening the front bolt, then lightly tighten the back. Once the frame is back on the body and perfectly centered torque the two down completely & evenly. You want a perfect seal!
That I believe should take care of your issue.
This is what I done but maybe I didn’t perfectly place it back so any disturbance to the marker it comes back out of place.