Thank you guys. The shifter was acting in a somewhat ratcheting friction action, as you, TiBikeGuy, better expressed as not clicking into each position.

I did insert the cable while in a middle gear because of the required bending of the cable at the highest gear; the insert hole required more finesse if I were to insert the cable at the proper gear. I'll be sure to try cleaning up the shifter/reinserting the cable the proper way. I expect these two strategies will solve my problem. Sorry that this thread was a bit elementary; I'm not very familiar with brifters at this point.

Thanks again for your advice guys!