problem solved!
I bought the Camera locally in Plymouth at the London Camera Exchange, so I went back and asked them what they thought the problem was and after trying a new grip to make sure it wasn't my camera, they just replaced the grip on the spot. They are a 'Pro' dealership so they could have just put it on a priority repair and kept their stock, but they chose to look after me.
So I'm glad I didn't buy from another country or eBay.
In fact, if I had done that I would have settled for a 400D in my ignorance, but after handling everything in the shop (this is so important) then going away to research, I became the proud owner of a 'proper' camera which also suited my style of work - something most research would fail to show up.

Thanks Dan, I tried, but no joy.
It did work at first and I thought you'd cracked it, but then it just stopped. I'll have another root around.
I think I'll wait till after Christmas to get it fixed tho'.

Before I head off to the camera shop and loose my battery grip for a month, has anyone come across a problem of the shutter release not working on the grip?
mine was fine when I bought it in Aug, but now it's unreliable and only focuses if I press it hard enought to release the shutter.
I don't use it very often (keep forgetting it's there!)

Looks like it is worth having a decent teleconverter in the kit - used judiciously.
which makes should I consider?

Thanks guys, are they more acceptable on prime lenses where you can afford to loose a few percent?
I have just bought a 50mm 1.7 mostly for shots of the children and reversing for macro (thanks for that idea for Christmas). It may turn the 50 into a more discrete portrait lens or just ruin it....?

if I get a tele converter for my K10 is there anything I need to know or is a tele converter a tele converter?

What happens to auto focus lenses?

I have a Tamron 70-300 is there one that is particularly suited to that?

No I never did get one, it was just an idea, but right now I am having fun at the extreme other end - photographing the hair on fleas legs with a load of old lenses taped together. Actually Loki has stopped breading fleas now that the drops have kicked in, which is very dissapointing!
And there's an eclipse on the way, so maybe I'll wish I had bought a mirror after all...

I think I will hang around for one of the better ones, I like the images by niblue, mirrors clearly have some interesting applications. Think I'll need a stronger tripod tho'..

Is there such a thing as a Paragon 300-600 or did my seller mean pentacon? (I hope)

OK guys I'm trawling the internet and I've come across a Paragon 300-600 mirror. any ideas if this is better or worse than the Centor? I am just going to be messin' around, but I might as well get a half decent 'telescope'.

Well sounds like they are er...inexpensive for a reason.
but might be worth having fun with tho'.
I'm up to 300mm at the mo', do you think the Centor would be sharper than my Tamron with a converter? or able to do something interesting?