We have saved a number of different  larger Cycads that other collectors  had all  but given up on, they had tried  unsuccessfully to reestablish them, they   had them too long without leaves and   roots some had pockets of rot, or a heavily  callused  base, and most of them were  very light in weight. We took the plants  and cut the stem back to good clean tissue  completely removing any rot or callous.   We then treat the wound with hormones  and fungicide, we use a black can that’s not a whole  lot bigger then the stems diameter, maybe only  1” or 2” of clearance around the edges, this will help hold the plant solid.  We put the bottom 2” to  3” of the  stem into new washed pumice, it is very important to make sure that the can and pumice are new or  sterilized every time you do this, the knife should be cleaned with  bleach before you make your final cut on the stem this will help stop  the spread of fungus. We then place it in a warm spot, bottom heat works the best, but even the concrete around a swimming pool will   work. We also found that the plant benefits from wrapping a ½” to  ¾”  layer of  moss around the stem, we hold it in place by wrapping it with   string or light wire, we keep the moss away from the crown at the top and from the pumice at the bottom about 1”, this way we can keep the stem  damp and humid without the base staying to wet. This helps re- hydrate the stem without waterlogging the base. We check the bottom   of the stem every  3 or 4  weeks until we spot new roots starting , after   that we won’t disturb it again until we plant it months later. it is important to use a soil with good drainage and the right pH level. The  roots are very fragile; you should be careful not to damage any. I always get someone to help me, last thing I give it a light fungicide drench.