Hi All and Merry Christmas!

I am a bit stuck. Just at the latter stages of finishing the head gasket change on my 2.2, all has gone well so far, until now. I cannot get the inlet cam gear to stay at TDC. The exhaust one is fine, and I have checked that the crank is still correct (notch in line with the spike). The inlet cam must be pushing against the cam followers/valves as if I rotate it to TDC, it springs away when I let go.
Don't know what to do, as I have tried aligning the belt on whilst holding the gear in place, but before I can rotate the engine the gear will spring back and there is slack on the belt between the two gears. I am reluctant to rotate the engine with the use of a third hand, as once I have done that I will have lost TDC and have no idea what to do!
Any suggestions? I thought maybe I had put the inlet cam on rotated by 180C but that cannot be the case due to the locating lugs on the gear. So just stumped now...
Look forward to all the suggestions coming flooding in!
Cheers
Phil
