Change Master Collation in Multi-instance Cluster

Hy Guys,

SQL Server 2008 R2 Ent 64 bit.

Cluster with 2 Servers (SrvA, SrvB).

The Sql cluster is made up by 2 Instances: vSrvA\Instance1, and VSrvB\Instance2 (both working correctly and accessible anywhere across the network).

ISSUE:

Changing Master Collation on both instances.

Attempted several time but unsuccessfully (I have also checked teh log, but I cannot see nothing of relevant) following the procuedure provided by Microsoft and in other posts.

Please, anyone could provide a procedure to change Master Collation in Multi-istance Cluster?

Kind regards