A thought on pricing: per machine is probably the best. If you do per zerk, customers are going to try and do one zerk on the machine, and track it on a per machine basis, instead of per zerk (which is what you want).
The employees will then learn this, and grease that one spot. The customers won't see the value (since the data will be crappy), and might end up seeing it as a boondoggle instead of the valuable service that it obviously is.
Some other thoughts, and a reason to sell per-machine: early warning systems for parts that are about to fail. If a part is leaking grease, and using up more than it should, warn the customer about it. Could be a gasket going bad, but in any case probably needs maintenance attention.
I think you'll almost certainly want to have "Contact us" pricing. The cost of a zerk being poorly greased depends greatly on the value of that machine to the plant and the cost of that machine going down.
A thought on pricing: per machine is probably the best. If you do per zerk, customers are going to try and do one zerk on the machine, and track it on a per machine basis, instead of per zerk (which is what you want).
The employees will then learn this, and grease that one spot. The customers won't see the value (since the data will be crappy), and might end up seeing it as a boondoggle instead of the valuable service that it obviously is.
Some other thoughts, and a reason to sell per-machine: early warning systems for parts that are about to fail. If a part is leaking grease, and using up more than it should, warn the customer about it. Could be a gasket going bad, but in any case probably needs maintenance attention.
Good luck!