air tank

i have a sonoma with a 6 gallon tank i just got my 4link done and now it sits lower. when they did my four link they did not raise my airtank which is under my bed,when i draged it i scraped what was suppose to be a release valve but really was a screw of now the head of the srew is gone but the screw is still in there and there is a big hole in the middle of the screw where all the air escapes through how can I get that srew out or what is the best thing to do?