I did not have the rubber fail but:
I had my trailer at a trailer sales place(not RVs) to raise the trailer. He found the Equa-Flex welds or whatever were failing and tried to get them replaced thru Lippert with no luck.
We bought this trailer used, a year old so I do not know the history but seemed well taken care of. Lippert and Crossroads both say the trailer did not come with it, however they were advertised with it and the Equa-Flex logo is on the side of the trailer. Oh well.
It seems to me I read somewhere that there were some made with rubber that cracking and were replacing them. I will see if I can find that for you.