Originally posted by Des I think the problem can be overstated. There are many thousands of cameras with the green solenoid (e.g. K-30, K-50, K-S1, K-S2, K-70) still in use. Most will never develop the problem (I had two K-30s and neither had any issue.) Others will have been repaired and never get it again. You hear a lot about the problem ones, but not about the vast majority that don't have a problem. My guess is that these cameras have at least as long a useful life, on average, as their contemporary rivals (e.g. Canon Rebels, Nikon 3XXX and 5xxxx series) - maybe longer, because they were often better built in the first place.
Having repaired a lot of Pentax bodies and having studied the forums, offers on ebay etc. I would say you are far off with saying the problem can be overstated.
I estimate that it hit and hits 30% of all Pentax K30's and 30% of all pre December 2015 manufactured K50's + K500's (never built after that time actually), as well as K-S1's and K-S2's. What brings me to that number is personal experience within family, relatives and friends because I recommended Pentax, they know me and listen to me. From that moment on when ABF became an issue, I told them about it so that when the dark-image-syndrom would happen it can be fixed by myself.
And it did happen to quite a few, so I started to repair them anyway, now not a single of them contains the China-Solenoid.
I take it that my experience can be extrapolated pretty acurate. But ´only my wife and myself are those who use their DSLR Pentaxes every day or almost every day.
My wife has 3 x the K-S1 and two of them developed ABF.
After Dec. 2015 the problem went much lower but sometimes does happen. I don't own the K-70 myself anymore but I repaired quite a few as well. And yet I can say that the percentage of post-Dec. 2015 going off dropped considerably.
You won't hear about many of the problem cameras at all! Many users are just pissed about it and get rid of them similar to smart-phones. We live in a throw-away-society, thus why should that be different to DSLR's, no matter what the fault is?
Also many cameras don't have a long and useful life as we do. Many use them in the beginning, many just on holidays etc. etc.
I can verify that as well with the low shuttercount of cameras I repaired.
Almost every day Pentax bodies with ABF show up on ebay worldwide. But those are just the tip of the iceberg.