Chainsaw Repair

HI group: I have a 910 E and as I was cleaning it from a lot of work a black cap / cover came off the gas tank vent. I think it came off as a black piece went flying when I hit it with some compressed air; and now it bogs and will not stay running and if moved the wrong way gas spills out. So I am asking if anyone can help as I have looked all over and tried to find this cap with no luck. I did find a filter piece but that is not what I am looking for. ANY HELP would be GREAT Thanks a ton.   It starts right up like high speed and dies and then will not start until it sits for quit awhile.

No I have looked over and over and do not see the gas tank or the cap that goes on the vent. I tried to post a pic when I opened this topic but size was to big. Any ideas??I believe it is some sort of rubber piece that locks on to a recessed area at the top of the vent I resized pics and posted

Look at page 2 IPL far left. looks like you are missing the tube and bronze breather deal on end of tube.

Like I said I am just guessing. 

Any idea where my best chance of finding the parts? These older items just don't have much resources like the newer stuff.

  Thanks a BAZILLION!!