collections/<collection>/leader_elect/shard<x>/election
A healthy SolrCloud cluster presents as many core_nodeX as the total replicas for the shard.
You don’t want duplicates or missing nodes here.
If you’re having trouble getting a sane election, you can try deleting the lowest-numbered entries (as well as any lower-numbered duplicates) and try to foce the election again. Possibly followed by restarting the node with that lowest-numbered entry.
collections/<collection>/leader/shard<x>
Make sure that this folder exists and has the expected replica as a leader.
collections/<collection>/leader_initiated_recovery
This folder can be informative too, this represents replicas that the *leader* thinks are out of sync, usually due to a failed update request.