I would offer the 'in-house tech' anything I could in the way of help or education/chewing the fat about the forklifts he takes care of. I would want to become their friend, as well as their being my customer, (take them fishing if they spend 6k a month with your company).
It always seems important to me to remember that the the butt you kick when you are on the way up may be the butt you have to kiss on the way down.
You may wind up working for that 'parts changer' some day, and any help/education you gave them when they were in need of "Special High Intensity Training" (or the acronym thereof), is/should be 'a good thing' [even if "no good deed goes unpunished"]. Besides, your company may hire him one day and you will need him to cover for you while you go on vacation...