What I ended up doing was looping a thread under the offending stays and hanging the model from that thread. That stretched out the stays so that they were straight. I then coated the stays with glue while the ship was hanging so that they had some stiffness to them and wouldn’t sag though they didn’t really meet the mast. So then, I tied the loop to a point higher up on the mast. So I’ve got a pretty unsightly clump of thread-knot at the top of the mast above the royal spar but I think that will be less noticeable than sagging stays.
Ultimately, I think the cause of my problem was dealing with the ill-positioned holes for the stays in the bulwarks underneath the ratlines. The hell with that. For now on I’m just drilling new holes whenever possible. That gave me a reason to replace my 40 year old Dremel tool with a variable speed, flexible shafted model.
Self taught, persistently behind the times, never up to date. AKA ~ jeff
More verbosity: http://petiteguerre.blogspot.com/