[Hybrid tellies]

I don't know what happened at RRI but something major did from producing one of the best dual standard TV's ever with the A640 to the disastrous A774 was a big retro step. We found the A774 was heavy on tubes and LOPT's, PCL805,s suffered a high mortality rate due to being placed just above the mains dropper, on off switch failures, very difficult to cure background hum on the sound even after RRI bought out various mods to overcome this.
Then there was the fault of intermittent poor sync, line tearing and hum bars which meant tipping the set on its front set to resolder all those chassis lugs on the main PCB, an official mod came out to link all these lugs with wire links. Some of the last A774 sets already had this done.
I still have somewhere a bag of those blue replacement tuner slugs, which was also a problem on the A823 colour sets which used the same mechanical tuner. We did so many of these tuner repairs I can still probably do this job in my sleep.
Once you had overcome these problems and with careful set up the A774 could produce a fair and reasonably stable picture but even at best was not a patch on other black and white sets of this era including the earlier RBM A640 and the 625 single standard black and white sets from Decca, GEC, ITT and Pye.