I only have one cog on the back wheel but mine doesn't sit evenly either, However, the center of the rear brake is above the center of the tire. I think it is just another Brompton adaptation to the fold. As others have said you might want to check the shifter chain adjustment. you screw the chain pin all the way and turn back a 1/2 turn or so so the chain bend is in line with cable. Put it in third, when the cable is slackest, and then shift to 2nd.The cylindrical part of the screw shaft should be just appearing where it can be seen. Sturmey A has these instructions. Every time I pull the rear wheel I do the screw in and back 1/2 turn thing and the adjust the chain tension as above. I also have been running it with about a cc of synthetic motor which seeps out quite a bit. I got a vet syringe and flip the bike on its side and inject the oil into the axle where the chain pin goes. Messy in the car due to the dribble but it shifts and runs very nicely.The tiny quantities of oil are cheap. and SA mechanics are far and few between here in Wyoming. If I do get it serviced i can go back to a grease lube scenario but for now oil is best for me. With the chain adjusted and the hub properly lubed it is fairly quiet. When it gets a little noisier I put in another few drops. tough to do without the syringe, though.