Yea, I agree if you have FE MBSY shoing on the channels it's the carrier side having issues. I have cleared this before by disabling the span and re-enabling or while the T1 is up enable the channels that are showing FE MSBY by entering this command. ench l ch, l being loop number and ch is the channel.
If you know what d-channel it is then diable it in load 90, then go into load 60 and disable the span and re-enable, if AUTO is set on the D-Channel then the D-Channel will attempt to establish automatically when the loop is enabled, if not run the command below.
>ld 90
.dis dch x
>ld 60
.disl x
Then try to re-enable it
.enll x
or
.ench l ch