I found that giving them one repair task to focus on across a bunch of bicycles, worked really well to develop quick expertise without overwhelming them with having to learn the whole bicycle. One person learning brakes, another learning gears, and still another on headsets for several sessions really got them comfortable with what they were doing. So much so that then they could show someone else how to do it. Then I would rotate them.
Couple that with Jim's videos and that's a recipe for not having to handhold.
Something I've been doing outside of bicycles is having everyone share their skills, experience, interests, superpowers, and what bugs them about being on teams. Then we go through what trust, openness, courage, empathy, and respect mean to us and what those behaviors look like. We write it down in case we need to come back to it later, which has happened. Then each week we spend 10 minutes going through what worked well, what didn't, and what 3 things can be improved. In the next session, we start by assessing if we made the changes and what the results were.
Good luck.