My DR plant was doing fine and has started new growth from the caudex. Now the branches and the stem feel to be getting soft to the touch and the leaves are falling off . Should I cut the branches? Should I cut the stem down to the caudex? Should I repot and wash the roots?
I only water it about every 3 or 4 weeks when it it dry I use a moisture meter.

too little light with too much water will do this

cut main stem about 1/2 way up from caudex ...... if you see any discoloration * other than white or green *
if what you see is: tan, light brown, dark brown or black - then, cut main stem 1" down ..... if you continue to see tans, light browns, dark browns or blacks - keep taking 1" slices until you only see white or green .....

tan, light brown, dark brown or black is rot and it will continue to spread if not removed ...eventually killing the plant

find a brighter sun-lit spot or purchase a grow light

water very sparingly