Y'know I don't think there is any mechanic for that in AToW or the Companion but maybe looking through StratOps for the repair rules could be useful.
Tech Team: 7 personnel, where 1 is tech and others are astechs. Target Number (TN) is based on skill of tech, smaller number is better skilled. If Tech Team is less than 7, modifiers apply to TN: +1 for every missing astech. So if wheeled light vehicle were to break down and there are four personnel where one is veteran tech, base TN is 6 (of the veteran tech). 2 other personnel could have some technical training so they can help out as astechs. There we have veteran Tech Team of 3 personnel. Veteran Tech Team short of 4 personnel would have TN of 10 (6 for skill +4 for missing personnel) to repair the vehicle, + any other modifiers in MASTER REPAIR TABLE and what GM might deem appropriate (+ for lack of tools & parts, - for Extra Time etc.)