Possible Clues:

• Modernize, maybe
• Row about defensive facility put back later upgrade
• Equip with new parts — bent lever ultimately lifts it
• Characters in riot fret about something modern being introduced
• Engineers needing time with advantage not initially getting extra component
• Make backwards-compatible
• Install new parts, strong girder finally put up over it
• Substitute new parts for old
• Upgrade, as aircraft
• Keep interrupting row about updated component