Thanks for all that, very helpful. I think that the drive belt is too loose. And this is why I'm having the issues.
I found this video
, if you go to 2:18 on that video I note when I use a bar I notice that the pulley doesn't move hardly at all, nor does the 'Arm' underneath it I tried everything. I think this may be why the Belt isn't tensioning correctly - Any suggestions gratefully received
I found this video