Thank you bforbes for the link.https://www.camerashuttercount.com/
I uploaded an unedited pef and it returned a result of 37,064 on Pentax K10D so it got the camera right.
D'you reckon the counts right ?

Thank you both

Unfortunately the thunk occurs when switched off and when switched on and with SR on and off. I noticed it the first time I tilted the camera from landscape to portrait while taking pictures. Testing it again now it is doing it when tilted on its axis in the same plane in use. In other words not laying it on its back or front.
Just did sensor cleaning and could hear something going on and the clunking did not happen on moving camera. however, now cleaning finished and camera back on, the clunking is still there.
I suppose if all else is working I should ignore it. Probably nervous about just spending £100 on my first digital.
Thanks again

Umm, in 1988 my wife dropped my 1970s Pentax ME super over the first floor landing's banisters down to the Welsh slate floor of the hall. I continued to use it in 1/125 non-battery mechanical shutter mode, via a paper clip down the new hole where the button was, no metering and I taped up the awfully bent back each reloading of film, to light seal it and keep it shut. Poverty is the mother of improvisation.
Around the same time my toddler son grabbed my SME arm by the Stanton Triple EEE cartridge and bent it up over its mount from which there was no recovery possible. Oh, sorry, wrong forum

Black tape proved useful again with a recent ebay lens with no cap. A few turns round the lens rim and a plastic Bisto lid fits great.

After more than 50 years of film photography I have bought a used digital camera body. Cost of film, paper and developing beyond me having just retired. As you can imagine I have more than a dozen various lenses all with their own success and limitations on my K10D
As you can see from the title I have a worry. It doesn't move far - just enough to be obvious that there is play in something and it feels like something quite substantial. Apart from flash always whiting everything out and a few unaccountable reciprocity probs the camera appears otherwise ok.
Has any one any comments please ?

In regard to actuations, I got nothing from Photome but in top right hand corner of info is 100-7269 does this imply 726,690 shutter releases ?