Got an hour this morning before work so took a bench into the garden (wife has new puppy which likes to be with me, unsafe in the garage)
Proceeded to install the new +040 IMD pistons on the rods. First circlip as soon as I applied any pressure, yep pinged off to God knows where... Bugger!
Started to install another one of the remaining 3, assuming the first one was gone forever and resigning myself to reusing an old one. Found the best way to install these awkward blighters is to just push the first one down the hole in the piston edge first then turn it once it's in, then use a gudgeon pin to seat it in the grove, install the pin and rod then with a pair of long nose pliers and a piece of tape stuck to the clip, seat as much of the clip in the grove as you can, then use a gudgeon pin to push the clip home. Made it really easy and if the clip pinged off again it would have a piece of tape stuck to it to slow it down and make it easier to find in the grass.
After trying an old circlip in there was too much sideways movement in the pin so had to start looking in the grass for the lost one. I decided to start at the far corner of the garden(had to start somewhere, and I had no idea which way it had flown) weird thing is, as soon as I looked down... There it was.
So now pistons installed on rods, rods onto the crank, crank into the cases, along with the cam and copious amounts of oil on all the bearing surfaces, cases done up, crank end float rechecked... 0.03mm ( just a gnats sneeze over one thou) result!
Tomorrow the timing gears etc.
Thanks all who've advised and helped.
Jase