Front derailleur won’t shift into third gear

Total mechanical noob here so I appreciate your help and patience. Have a Mid 2000’s Giant Sedona Cx. The front derailleur won’t shift into third gear.

I have tried a few things to see what’s going on. I’ve attempted tightening the shifter cable, adjusting the high limit screw as well as adjusting the derailleur on the frame. All with no luck.

When attempting to shift into third, the shifter doesn’t seem to engage the derailleur until it is pressed at least 75% of the way down. When pressed all the way down the derailleur isn’t pushed far enough to even contact the chain yet alone push it up to the third gear.

Given this information I suspect the shifter may need to be replaced. I’d just like a better opinion before I go any further. Thanks for any help!