The heads of the bolts that secure the flute tubes to the flute tube supports prevented the firewall insert from slipping in. Basically, the recess fits inside the flute tube supports, but doesn't clear the bolt heads. To remedy this, I needed to move both supports outboard the width of the bolt head. Thankfully, the C- channel that was used to make the supports was wide enough to just drill the hole a bit off center. This way, the supports remain vertical and use the same firewall holes. The first two pictures show the problem bolt heads and the third photo has witness marks at the top of the supports. The next entry will show how far the new holes moved the supports outboard.
