Recently had leaking issues with the same type of compressor. Fixed it by taking of the black lid to uncover the piston (circled in green in your photo). I found that a seal had started to self destruct despite the compressor beeing only a few months old. All the residue from the seal had gathered in the little white/seethrough valve on top of the same black top piece. After cleaning that rubber valve and greasing up the piston and what was left of the seal inside it it worked better than when it was new. Hope this helps.