That place does sound kind of shady. I've grown into the habit of watching mechanics for at least most of the time. Unless it's a multi-day job, of course. Something like this should only take an hour at most, and I'd stick around to watch them. If for some reason they get upset with you watching, tell them that it's your car and you're just curious about how to do things with it. If they don't like that, they can put **** back together free of charge and expect you to not come back. I haven't had any complaints from mechanics, though.

If you wanna try it yourself, PM me. I'll walk you through it one way or the other.