I see this thread is quite old, but allow me to tell you about my saga with 989s when I was still living in England.
I heard a pair at the London Hifi Show soon after they launched and, well, let’s just say they blew me away completely.
So I went home, offloaded some gear and ordered a pair. I won’t say where from because the very well known dealer is still trading and had nothing to do with the awful issues that started almost as soon as I fired up the first pair out of the box, making that crackling and thudding noises that are familiar to many ESL owners up and down the years - but right out of the box when brand new!
My dealer, who was amazing throughout and even visited me to check things out, then arranged for a new pair to be delivered. Same issue. This went on until I reached, wait for it, the 5th pair and they ALL had the same problem...
As a pattern had formed, I decided to bow out and was given a full refund. It was heartbreaking.
It transpired that it was around this time that Quad ESL manufacture had moved to China. From what the OP is saying here, it looks like the glue issues persist to this day. In fact I know they do through conversation with someone who repairs Quads as a hobby. He is often doing rebuilds to overcome this issue, even on the latest pairs.
Prior to this purchase, I had owned a couple of pairs of 63s at various points. I loved them but this was the time in my audiophile career when I was curious about lots of speakers and I inevitably traded them for something.
Another audio dealer friend would generously allow me to take home his shop "retro display" pair of 57s every now and again. I absolutely loved them, even though they clearly needed some servicing.
Fast forward to moving to the States and, after many years of casually looking, about two years ago I located a very unspoiled 1978 pair of 57s and I pulled the trigger.
So far so good, and I have had the rectifiers rebuilt and also had the treble clamps fitted. Nothing comes close to them in terms of that core strength of Quads, the irresistible mid-range.
The 57s are definitely a forever speaker. I do have a cone driven pair of Thiels as my daily drivers, but the Quads come out every few weeks when I lust after more of their magic.
It’s horrible to read that people are still buying their dream speaker, at huge expense, only to be let down by the build issues. The solution is to get an expert repairer to strip them down and make them good. Personally I think Quad should paying for that each and every time for pairs that are still under warranty.
Not the revered company it once was. I highly recommend Ken Kessler’s book "Quad The Closest Approach" that reminds us of happier times at Huntingdon.