On the other hand, the SQ-A darkslide detection in the film backs is the worst safety lock I have ever seen. The slide must be perfectly inserted, otherwise the camera doesn't detect it and let you shoot (yes, I had one completely blank roll because of this).
Maybe there's some need for service? On my ETR cameras this lock has worked always perfectly. You need to remove the slide quite a bit to be able to shoot.
This was discussed before, the big difference between GS-1 and other Bronica formats is the in body electromagnet going weak ( my understanding is this particular design is not employed in other bodies ). It stops triggering in-lens shutter. It's a common problem.
We must be very careful because it might be just a case of cleaning and lubrication. And, if weak magnet is the case, such solenoid magnets can be remagnetized as well (for example M. Vettore documented how to remagnetize the solenoid magnet inside ETR and SQ lenses).
They messed up on that, possibly under-specked electromagnet that could not stand up to normal use, to me inexcusable,
Wait until you see how resilient or reliable are the Pentax 6x7 film advance gears... And , again, in the mind of the people the 6x7 is a reliable field-camera worthy of taking on a safari.
Something went wrong with GS-1 system definitely, because I think it is the only one that Bronica never did more iterations. Perhaps sales were lower than expected compared to SQ and ETR, that were developed much further.
Sales, probably.
ETR was released in 1976 and SQ in 80 or so. The GS-1 came much later (1983), and by the time the GS-1 was released, the 6x7 market was already dominated by the Pentax 6x7 system (introduced late 1960s) and the Mamiya RB system (introduced 1970). So the main competitors already had at least 13 years advantage.
It also didn't help that the Mamiya RZ67, also an electronic 6x7 camera, was already on the market (1982). This means that Mamiya had a huge array of available lenses -- in fact up to four generations of lenses, the early ones, the NB ones, the C ones and then the RZ67 lenses -- from fisheye to extreme telephoto. The GS-1 was released with only 6 lenses: 50, 65, 100, 150, 200 and 250mm lenses, the GS-1 had TTL flash but this feature could be used only with one specific, small, battery-powered flash branded Bronica (!).
So perhaps it had a very tough market to break in.
And as a person who has owned 3 Mamiya RB67 pro-S cameras and four Pentax 6x7/67 cameras, I can sort of understand. Because if I want portability and lighter weight, there is the Pentax which also has very fast lenses overall (90/2.8, 105/2.4, 150/2.8 etc) and extreme teles. And if I want to work on a studio, the RB67 has the rotating back which is a major advantage.
The GS-1 tried to be a handholdable 6x7 SLR that could also be perfect for the studio but I think the lack of rotating back hit it. And this is a no-win situation: if they added a rotating back, the camera would have to be a much bigger camera, negating the "light", "handholdable" advantage.
The ETR is much smaller and lighter so it wins in this regard over the competition, and in 1976 the ETR was miles ahead of the Mamiya 645 cameras (their only competition, the Pentax 645 didn't even exist.) In the same way than the Mamiya RB67, when introduced, was a great leap forward over the Hasselblad 500C or C/M, and thus could quickly get market share.