0813 starter motor problem?

I have A 1991 Cargo that keeps developing a starter motor problem after about 12 months. I replace the motor with a new one and then it starts with the same problem all over again the following 12 months. When I turn the ignition key it just clicks and will not engage. I have checked all the earths and batterys are ok Has anybody got a suggestion, could it be connected to the fuse box ?

douglad Burgher
July 2010