thank you thank you thank you. I mean to try air compressor at the next chance. But first, two curiositys.... ____ If i remember correctly, someone once told me that air compresses, and water does not, then.... what are the important dangers of using air, what things should i absolutely understand if nothing else..... ___ secondly, considering that: IF the leak happened to finally leak out from under the new driveway/retaining wall, being at the very center- the worst case i would imagine , or even under the new house addtion (the square piece in the bottom/south/lower)...... it would seem that all reasonable solutions, include re-routing the lateral from the zone manifold around the front, and under the driveway to reach the top-right corner sod. Or moving the valve near the MV, and continuing the wire out there from the current manifold...... If the leak is under the house or drive, (which connect: concrete-to-concrete), making up the ultimate edge of the property all concrete, and the only apparent solution is to re-route around, Does it make sense to use air and prove to myself that it is infact under the house? (if infact.) My latest evidence of trying to determine whether it's "before the house/drive", or "under the housedrive" is: I took off the double-elbow gutter to spout connection, and used a spot light to look down the spout into, atleast one drain tile.... when the zone is on, and leaking, i see no flow thought the drain tile Tee below..... yet, when i turn on a water hose, fed into the spout, water exits from the same drain tile piece as the leak.