I can't say for sure yet that I've fixed the problem, but there are a couple important notes that have brought me closer to solving the plink/honk issue on the low E string. I noticed posts about damping the strings above the nut. I used an elastic and it helps with the audible acoustic overtones, but I don't think it affects the Plink/honk. However, vibrations below the bridge makes more theoretical sense to dampen. So I happened to have some silicone tubing .062" dia. and I fished it underneath the small space beneath the bridge so that it dampened the strings below the bridge. I feel like there has been an improvement in the sound. A larger diameter tube is ideally needed, or a 2nd .062", but that's a tight fit. I'll continue working on that. Next, I cannot get rid of the fret buzz on the low E, no matter how uncomfortably high I set the action at the bridge. I know that contributes to the odd overtones. I may loosen the truss rod although there seems to be enough of a arc in the neck. Anyway, it's a 69. If anyone else gives the bridge dampening a shot, please shout out. Maybe we're on to something here.