Finding a workshop manual for the BX24 might be helpful. I don't see one at kubotabooks.com, but there is one for the BX25 if I remember right. Download it and take a look. Might give you some help, who knows?
Seems like most steering issues on the BX is due to issues with the hydraulic steering cylinder. Mine is showing signs of this issue...BX2200...19 years old now.