Problem of LHB Microprocessors

There are 4 makes of microprocessor in LHB RMPUs. All have different circuit designs. Now the problem is that being high value item, we can't make them stock items and being different generic designs, we can't make some parts as stock. Now when any of the part fails we generate non-stock demand and then coach runs with microprocessor bypassed till procurement.
Most of the time, we find staff not so skilled to find out which card, IC or PCb has beome defective in the microprocessor.

Any solutions?