What can we do about my husband's ex-employer who gave out bad paychecks?

In addition to what the prior poster said, you should contact the New York State Department of Labor.  Not being paid for work is a criminal act by the employer, which the state will investigate.

1) If your husband was not paid what what was supposed to be paid, he can sue the ex-employer for the money. That is the only way to get it if the employer won't voluntarily do the right thing.

2) In addition to suing for the unpaid wages, you can sue for costs incurred by you due to the failure to pay: e.g. bounced check or late fees; the costs to move if you are evicted; etc.

3) You could sue in small claims and represent yourself if you don't want or can't afford an attorney.

One issue to consider: whether the former employer is still in business or otherwise has mony/assets. If not, even if you win, you may not be able to recover anything.