I called about 10 shops trying to find high-pressure tubing to repair the cut I had made in the unloader tube and then more tubing to install the T farther away from the heat of the compressor (closer to the pressure switch). When I finally found the tubing, I was persuaded to abandon the automatic drain in favor of a good old fashioned ball valve. To make it more accessible, I was advised to come out of the bottom of the compressor with a 1/4" street ell and to bring it to the front with a 6" galvanized nipple. Works great. (Time: 2.0 hours)
