Thanks for the link....very interesting and useful to know

Interesting video.
How easy/difficult was it to remove the camera case and access the part ?
Is removal and replacement of the part tricky/delicate?
I ask as someone who has past experience of repairs to electrical equipment, as I won't rule out attempting this myself if need be.
I certainly have no intention of spending over two hundred pounds for the repair.
What I can't understand is why Johnson's have to charge a service price to carry out a repair.
(If I needed a new headlight in my car I wouldn't expect to pay the cost of a full service)

My K30 was purchased in January 2014 and the warranty expired in January 2016.
The first failure occurred on holiday in June 2016. With the camera set to manual, I exposed a scene and took the shot only to find that the photo was black. I immediately took a second photo of the same scene using the same settings and the photo was correctly exposed. It happened numerous times on the holiday and since. The shutter count is 6000 plus.
I see from this forum that it is a common problem that was known about at the time of my purchase.
Johnson's (UK repair centre for Pentax/Ricoh) told me that they are not aware of a problem with this model, but this forum would suggest that they are.
I am contemplating sending it to them for an estimate and taking it from there.