I am in the process of selling my home and have encountered some pretty bad wood rot in a threshold that houses two fixed french doors and one practical door. The rot is bad only in places . I realize that tearing the frame out and replacing the threshold is probably the ultimate solution but I can't afford to do that now. Are there products available to fix this problem adequately and make it last? If there are please specify or point me in the right direction if possible. Thanks for your help!