For context I had lazz send the gears back to me for testing, not sure he mentioned this in his videos. I tried them in an e&c, lonex, and v3 JG gearbox and the spun perfectly, no issues at all, videos are up in anyone is interested. All I can put the problem down to is either some incompatibility with certain brand of 13:1 or as @Floperator says ensure the bushings are level. Seems like @Rogerborg has a neat solution. I wonder if its only 13's that cause the issue?