I've spelled that out for him, several times now, but no response. This isn't a lock problem. Condos, co-ops and similar have all kinds of problems like this. People parking in parking spots reserved for guests. People bringing commercial vehicles which aren't allowed onto the property. People letting dogs run where they are not allowed or having pets where pets are not allowed. Damaging common area elements. In all those cases the board of trustees, elected from the unit owners enforces the rules. And the legal documents that establish the owner's rights and OBLIGATIONS, give the board the power to fine unit owners if necessary. It becomes just like a maintenance payment, subject to the same collection. If they don't pay, the fines can be turned into a lien against the property, turned over to debt collection agencies, etc. Since the perp is tampering with common element property, the board should also call in the local police and they will likely at least have a talk with this person.