My 30 gal Kobalt air compressor gave up the ghost after only two years of service. It won't hold air after shutting off. It appears that perhaps the check valve is defective. I tried a few times last night and finally gave up. I ended up using my pancake compressor to run the rivet gun while I backriveted the stiffeners in the right fuel cell. The "Proseal" is a mess but as George Orndorff says, "Proseal is cheap." I'm hoping that ugly won't leak.