Trigger issues with g&g rk74 etu

[Keith_1701]

Used my g&g rk74 for the first time yesterday and noticed it fire fine on semi auto but when I switch it to full auto (without 3round burst activated) it would fire a couple of shots then stop. The only way I could get it to fire full auto was to press the trigger very lightly until I hear the switch click on the etu. Normal trigger pulls and it would be speratic.  Thought it might be the battery but it's the same on 7.4v and 11.1v lipo