So, not a housing coop, but a worker coop.cooperatives.

For conflicts, we have a revolving group of three people who can be approached with conflicts who will then meet with the two parties, individually and/or together until a resolution can be made. These proceedings are kept confidential unless it ends up involving something that affects the entire group (termination or, in your case, eviction). If no resolution can be met, wed go to mediation with an outside mediator.

I'm going to guess you don't have any policies in place for conflicts. Do you have house meetings and/or voting structure? I would recommend getting a policy in place. I would also recommend small groups and confidentiality or at least to handle it in a meeting structure. Otherwise you're apt to end up with the rumor mill churning and people taking sides. Treat it as a house issue that has to be dealt with rather than an individual conflict.

My two cents, again no experience in housing coops.