I’ve tried each of the three memory cards in this today (1 x SanDisk Extreme PLUS 80 MB/S & 2 x SanDisk Extreme PRO 280 MB/S.) I’ve not been able to replicate the issue. I had heard that there have been some problems with the Extreme PROs, notably when shooting video.
When the issue was occurring there was some latency in writing to the memory card, so on each card I formatted the content, and then proceeded to shoot on each of the setting for multiple shots (Low/Med/High). On one of the cards writing seemed to take a bit longer, but this varied in duration, and there was no issue with the images.
I have also had a fresh look at the sensor and there was what looked like a bristle stuck to the side of the sensor, perhaps in the e-front curtain. I managed to remove this with a lens-pen sensor cleaner. On closer inspection of the glass over the sensor, it may be that what I though was a scratch, could be a smear as a result of using a brush.
[/url]IMG_3037 by sastrugi1977, on Flickr[/img]
Look towards the top just right of middle of the sensor, what do you think?
[/url]IMG_3033 by sastrugi1977, on Flickr[/img]
Closer look…
I am going to take it into town to a photography shop to see what they think, aside from that I will return it to Jessops for a check over.