My opinion on the matter. If you already have good procedures, documentation, processes in place it's not worth it. However, if you want to get more business, it opens the doors to many new customers that simply require certification.
You would be out of business without customers so if they want to drop by I would be happy they are so interested in your work. Just how I would approach it.
You want to grease it until you see some grease squirt out the guideways, usually about three squirts depending on use. I suggest Super K05 grease. You can buy it on amazon.
We recently found a another grease called Super K05 Chuck grease (Super K05 Chuck Grease) I heard this new brand was created by some ex-employees for Autoblox or SMW, so they probably know what they are doing, and it's a lot less expensive and seems to work just fine.