Hi Hark,
Thank you & the others for all your help with my D7100 problem.
After trying all suggestions I bit the bullet & took it into Digicam, Adelaide for their take on things.
Long story short I pick up the camera complete with a new shutter next week, costing AUD$385, disappointing as the camera had less than 30,000 shutter operations from new, but sadly that's life sometimes.
Thanks again.
It's a shame to have to pay for a shutter replacement with such a low shutter count. As you said, it's disappointing. However, that body is a workhorse and hopefully will last you for a very long time. At least it's fixed so you can now enjoy using it!