Here is a good link.
http://www.bijurdelimon.com/fileadm.../Datasheets/35470_B_FIT_Meter-Units_DS-R2.pdf
Some of those metterng units have internal check valves. Many of the older machines had the manifold under a table so replacing them was a real pain. If your's is like that I would update it so the manifold mounted where it can be reached. Also mount the pump low so there is always a head of oil above the manifold. The higher the number the more oil is released. On your big machine I would have several units feed the ways so incase one plugs up you will have oil.
Also if some of the ways seem to be worn more, then there is no law that says you can't put a higher number in the manifold. I took a lubrication class years ago taught by a Lubrication Engineer at Trico and he said that many machines builders gave it the best guess on the lube fitting size and he said more oil is better then less oil. He also suggested mounting a pressure gage in between the pump and the manifold. The gage is a safety. If the pressure is lower then when it was with the new units, there is a leak or broken tube. If it is higher...something is plugged up. Also they recommend replacing all of them and not just 1 or 2. I have found that Trico, Showa and Lube are as good and less expensive the BiJur. Good Day :-) Rich