UPDATE: upgraded firmware, rebooted router, and can now find the needed screen.
Verizon and manufacturer instructions for M1424WR-I router say that power level can be set via control panel:
"3.5d Other Advanced Wireless Options
Clicking Other Advanced Wireless Options at the bottom of the Advanced
Security Settings screen generates (after clicking through the “Warning” screen)
another “Advanced Wireless Options” screen."
and
"Transmit Power
Adjust the power of the FiOS Router’s wireless signal by entering a percentage
in this text box."
I am not able to locate this screen. Has there been a change in the firmware or something?
Thanks for any help!