Night of the Living Dead
Have you ever tried to resurrect an old manuscript? Maybe you wrote a story--or part of a story--you loved, but at the time you didn't do the idea justice. So years later you decide to give it another go, and I know from experience that it never works out the way you think it will. Resurrections are messy, complicated, and fraught with the possibility of Frankenstein-like results.
My second Harlequin Temptation, Too Wild, is such a resurrected story. It was the fourth (I think) unpublished book I'd ever written, and after writing and selling more than a few others, it was a story I really thought I could do justice. First time around, I didn't yet have the skill to pull it off. Second time, I had to rewrite it from scratch, and it was...painful.
Really painful, like reopening an old war wound to dig out some shrapnel just because I wanted to use the metal in an art project.
I contend that old stories are best left to rest in peace. Maybe you can borrow bits and pieces of it, but it's easier if you just reinvent and create from the place you are now rather than trying to dig up old bones and risk having a night of the living dead happen right there in your writing space.