Bike (2018 Cannondale Synapse disc 105 SE) has about 42,000 miles on it. Suddenly it would not downshift to small chain ring. Shift cable is good. Small lever that was previously inside the shifter now sticks out and moves with no resistance. Maybe just a broken spring?
This shifter has cable brakes, not hydraulic. Reputable e-bay sellers have the R7000 shifter pair for $210.
Can the broken shifter be disassembled and repaired, or do I need to replace it?
Broken part circled in red.