I straightened a bent lower link the other day, took me about an hour............they are quite strong. The tight chain theory sounds possible, I have always thought it to be from incorrectly shimmed bearings, generally too tight. But I had one the other day on the back of a Comet that was flogged enough that the bearing housing has split. I think that he housing is quite a weak design, given the original ones made pre war were actually made of steel. So now i am of the opinion that it is generally caused by a lot of use and age. It is pretty rare to carry out a full restoration on these bikes and not have to replace one or both hubs. Like old cylinder barrel assemblies, I don't try and repair them, as the effort to fully strip a wheel to change the hub is far more than the cost of new replacements. Measure the outer OD of the bearing and the hub to see how much interference you have. if the bearing will press in without to much effort, I would lightly coat the bearing and hub inner wall with a light coat of bearing fit loctite, and press it in cold. If the interference is more than about 0.0015" heat the hub and simply drop the race in. I have never bothered to freeze the bearing, even with 0.003" interference with a hot hub the bearing will still drop in ok. Do not overheat the hub, the small area to be heated is not large, and thin walled. I mostly use an electric heat gun on smaller items like these. Good luck with it all.............. Greg.