Get the cage the right way up, what is shown as the lower roller is the top roller, just adjust the tension, they ran fairly tight. The plastic rollers may not be original?
The link to Disraeli gears is very useful :idea: .I had forgotten about it .It has told just what I needed to know for settling up a Simplex juy Record 60 rear mech,that I have been faffing with :facepalm: .