Boley 5lz oilers

I have a Boley 5lz with wick spindle oilers. Both of these are in the 'as found' condition: one has a thickish wad of wick and the other just a couple of strands. The latter always empties much faster than the former. I originally thought this was due to one bearing being worn, and causing a greater 'capillary' load, but swapping them over gives identical results.
The problem is, I have no idea which of the two is supplying the correct, or more correct, quantity of oil to the bearings. Can anyone help?