I do not have a 231 so I cannot say with direct experience on that one. However, for example, one of the most common failures on the small BX series Kubotas is the steering cylinder seals. Every one I have owned or worked on eventually had to have seals in the steering cylinder. In talking with experienced John Deere service shop people (who put new seals in the Kubota cylinder last time) they say there are rare few hydraulic cylinders that cannot be simply rebuilt by checking the surfaces and straightness and then putting in new seals. The kits are readily available for essentially all the common cylinder sizes.
Almost certainly you can get that steering cylinder rebuilt/new seals put in it ... and it need not be a MF dealer. Any repair shop that has experience with hydraulic system maintenance and repair can do it.
