Joe,
Did you operate on a fixed hourly rate or per quote basis? I charged an hourly rate. Tell him to not try to be a "bargain" because people were paying his employers' shop rate, so if he charges whatever that rate was/is then it is something his customers are used to. Basically his employer was charging for HIS expertise, since it doesn't take alot of special tools/equipment to repair TM's. Also he HAS to establish a 1 hour minimum and stick to it, even if he fixes a problem in 20 minutes; as long as he makes it clear to his customers that he charges for a minimum of an hour, he shouldn't have a problem.
Did you focus on owner operators or multi-truck operations? I didn't distinguish between the two; multi-truck companies were nice because they would usually have me out for scheduled maintenance becuase the owner's would not do oil changes, etc on their own; unlike alot of owner/operators. As long as they paid, I did not care if they had 1 or 10 units. Tell him to not be afraid to "fire" a customer if they are continually slow to pay.
Did you offer hourly maintaince packages ? Yes, I had some set-pricing for different services. But be careful here, because as you know, an "easy" repair or maintenance on a TM can become a nightmare! ha ha
Did you stock parts or just pick-up as required ? I did stock some things like plugs, filters, and the normal wear parts on a TM i.e., belts, solenoids, brass fittings, etc. If he maintained a good relationship with his employer, maybe he can still buy parts there with a discount. I never carried expensive parts and customers understand if you have to order them. Also, tell him to not be afraid of marking up the parts at least 30%. You can leave alot of money on the table over the course of a year by not marking up parts.
Did you offer Emergency service calls or after hour service? Absolutely! Make sure he charges more than his usual hourly rate for night/weekend service calls. He HAS TO REALIZE, just like a carpet cleaner, that his time is very valuable and he has a skill set, tools, etc, that is not very common and he should charge accordingly.
One thing that helped me in those days was that I arranged to be able to use a forklift at my firends business, so I could install TM's and also swap them out if a customer bought a new van. Also, tell him to hit up some small distributor's if there are any in the area that may not be big enough to pay a mechanic; he can do installs for them, warranty work and service work. He will have to share the Labor Rate, but it can be a great resource for jobs for him.
I am not an expert business man, but these are just some things that I learned along the way! Feel free to call me if you or your mechanic need any help! 505.934.1527.