Other than buying him out at an amount that is agreeable to you both, the only other thing that you can do is to approach the High Court to order the cessation of his membership interest under Section 36 of the Close Corporations Act.
A copy of the Act can be obtained here
It is, unfortunately, going to have to be High Court and you would have to obtain the services of an attorney. The Section says that the court can make any order it deems fair, which can include an order that you pay him back the loan, but if your attorneys address the issue of damages, chances are that the court will take that into account before it makes a decision on whether he is entitled to anything.
It is, other than a negotiated settlement, your only option, unless the association agreement makes provision for a procurement of the membership interest from one member to another.
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