I had a similar problem last winter - I broke 2-3 over the course of the winter and put it down to the cold. I tried boiling the parts to see if it improved the situation but not convinced it made much difference. I broke one late last year following a massive off whilst racing indoors (6 ft high table top collision
) but I ran the whole spring/summer/autumn without issue. The indoor racing was in an unheated facility so was very cold again, maybe 2-3 degrees!!
Doesn't really help you very much but I can sympathise with your plight...throughout the summer is was mega strong and reliable.