Here is the equipment classification sheet use it together with the maintenance sheet for more information

Equipment_Classification_List.xls (517 KB, 19 downloads)

Giga,
I would approach your situation somewhat differently.
1. The classification process you use is good, as it determines importance. The resolution may need some tweaking, since you have zero A's, thus losing one whole block. I suggest you shift the axes to the left and downwards slightly, so you do get a better balance of A, B and C (consider A=5%, B=20-30%, C= 60-70%). This will help schedule work better.
2. The classification determines priority and hence resource allocation to commence work, NOTHING else.
3. The timing of maintenance action depends solely on the rate of degradation and the acceptable performance standards, NOT on IMPORTANCE. We need to understand the degradation modes and rates to find WHEN to plan the work. Once we determine that, the more important jobs get the resources preferentially.