First port of call, decent quality fresh battery and plenty of air ?
Then try resetting the solenoid, de-gas and give it a good 10-20 trigger pulls with eyes off.
Next step, de-gassed remove the drive train from the back. Undo the velocity adjuster until it comes out of the bolt guide, take care not to lose the poppet spring, take out the poppet using an Allen key to gently push it through from the bolt guide end. Clean off old lube, apply a tiny amount to the white poppet face, a little to the poppet body o-ring and a little to the poppet body itself. Check any o-rings you come across while doing this for nicks, damage or wear and replace if needed. Re-lube the drive train ( don't go nuts) and you should be golden