I aquired this little 170 for a song not long ago. The issue is that the saw will not run with the air filter box installed. Remove the box and she runs like a champ. Seems to be choking out the saw when installed. I had another used carb that I tried to no avail. Same with the new carb. Compression is good (140) and the choke plate is free and clear of obstruction. I have done/tried everything I know to do. Anyone have any ideas or have had this happen to them? Thanks in advance.