ahh looks like stem rot the soil is too moist, and isn't drying out in time, thus the stem grows mold and slowly rots. i had some stem rotted basil plants, and tried to recover them by making sure the soil drains well and drys before i re water them. they ended up surviving, but they're growth is very slow, and doesn't have the potential as a healthy stemmed plant.
If I was to cut it and try and reroot it would I need to put it back in the dome or is it o.k. to go back in the 4x4 tray under the 1000w. Or do you think it would be better to just take cuttings ( clones ) and go from there. Or is o.k. to take cuttings from these plants. Need to know asap please if anyone has experience in this problem please get back to me thanks