I know this is an old post, BUT did you ever find a fix for these shifters? I have the exact same problem on three (yes three!) Shimano EF-29 shifters on three separate bikes; they shift fine in gears 4,5,6 and 7 but refuse to use gears 1,2 and 3. Weird. Anyhoo, would love to hear if there's a fix. Cheers.