Thank you for those comments. I checked the HSN and it is well sealed and I didn't see any signs of air leaks. I also looked at the front bearing and the crankshaft and didn't see any signs of wear or overheating. I ran a few more tanks through it and the highest temperature I reached was 220 F plus or minus 5 degrees. I also took the tempurature of the carburetor and noticed that it is reaching about 150 F. I'm not sure why my mephisto came with an aluminum carburetor, but I noticed that it should come with the composite carburetor. I ordered the composit carburetor and will give that a run when it arrives. Do you have a preference on carburetors aluminum vs. composite/plastic?