You should notify the landlord for the mal-function of the washing machine. Normally, the landlord is not going to repair it but the user, the tenant. You should check it in the tenancy whether there is such a clause for this arrangement. If you are going to buy a new one, you should get a prior consent from the landlord that the old machine will be disposed. You then have no duty to deliver the said machine on termination of the tenancy. It is not a good arrangement for the ownership of the machines be shared equally. This will also create a new agreement on the ownership of that machine when you are going to move out on termination of the tenancy.