The trans cooler lines carry "lubrication" pressure, usually 30 lbs. or so on the line coming from the trans to the cooler. The return line carries noticeably less than the other one.
Compression fittings have a habit of leaking if they're overtightened and the ferrules are distorted. The only good fix is to cut the line back about 1/2" and put a new ferrule onto an undamaged section of line. The quick fix is to eliminate the compression fitting altogether, and simply put a small bulge in the end of the line with the first stage of a double flaring tool, creating a knot to retain the rubber hose, then clamp it with a screw-type fuel line clamp. Trans cooler hose is a little heavier than rubber fuel line, and rated for higher temperature and pressure. Another good option is to use the same type hose that's found on the return side of a power steering pump.
Jerry
