I have a Warco MiniMill (X2 clone) and have found that the rubber bellows simply do not last in my workshop (garage). Generally they split in one or more of the creases. The originals did not last: I have used Arc Euro Trades bellows, they did not last. I have even tried gluing, using rubber glue from a cycle repair kit, pieces of old cycle inner tube over the splits – and still they split. I have tried using pieces cut from an old lorry innertube, but as there was no concertina effect, the tube just bunches up in use. The latest idea is to use one of Harold Hall's ideas, that of using folded cardboard "varnished" on both sides with polyurethane lacquer. Unfortunately, I still get bunching up because it appears that the varnished cardboard is too stiff.
My personal view is that it is caused by the cold winter temperatures in my uninsulated garage.
Peter G. Shaw