Thanks for the replies, awsome.
I did think about grease or WD 40 but to be honest it took two of us to get the lower limb out which can't be right.
Anyway, went to the shop this afternoon and tried another pair of limbs of the same make but i also took the weight up a couple of pounds as i'm on a limb exchange program.
Also, the mushrooms for want of a better word that the limb sits under were loose ie all the way in but easy to turn by finger so they nipped those up.
Result - the limbs seemed to locate more positively and they do not rattle or fall out unstrung. Loosed a few arrows off and then took the limbs off, EASY.
I was also shown that rather than pull the limbs off backwards, put your thumb onto the back of the riser and push against it whilst pulling the riser downwards and out backwards, sort of in a prising action and that made it more easier and controllable as well.
So, i've got my first Portsmouth on Wednesday so we shall see after a few ends if the limbs will still come out with ease.
Thanks again for the good tips
