Thanks Marc. Got it working now.
I was able to rack in manually by hand but still the magazine wasn't coming out. I managed to apply a little pressure down through the top of the pistol, using a screwdriver, while pressing the magazine release clip and it came out along with a single BB which somehow seemed to be jamming the magazine. Have tested with 7 BB's only and it seems to be working as it should.
Thanks again.
Robert