We have patent #5,853,128 which was applied for on Mar. 8, 1997 and issued on Dec. 29, 1998. We missed paying the final maintenance fee and have not tried to get it reissued before now. How long do we have before there is no way to get it reissued in any way?
The patent was pre-AIA, and therefore the best-case scenario is that it expired 17 years after issue. Therefore, as of Dec. 29, 2015, the patent is irretrievably in the public domain.