Wooden staircase repair

Description

Repair needed for wooden staircase. The stairs have sagged, and the screws on the left side leading to the second floor have become loose. I have temporarily screwed in new ones to prevent further sagging. I believe the stairs may need to be partially or fully disassembled and reassembled to ensure everything is in place. Additionally, due to deterioration, the handrail supports have come loose from their positions.