Thank you all for this good guidance.

We did everything suggested here: wrote the letters, sent digital photos, demanded (to no avail) the plumbers' report, requested mediation (but received no response), stated we would take legal action and finally consulted an attorney.

Our conclusions to date:

-We can't force the board remove the charge without taking the coop to court. Court & attorney fees would likely far outstrip the sum in question.

--We were advised, alternatively, to either file a claim with our homeowners' insurance, or to pay the charge and to try to recoup the funds in small claims court. In the latter case, we're afraid we'll find ourself unevenly matched, against the corporation's attorney.

Certainly seems to suggest a need for "abusive board" legislation.

Further suggestions very welcome!