I've been at a company for over two years. It's a small company with only around 35 employees and there is only one other person that actually knows how to do my job. However, he's frequently busy on everything else under the sun. I'm partly convinced that the business would fail if he quit. In contrast to this, almost every other employee does another type of job so they can bounce off each other quite a bit, while I either figure it out on my own or ask this guy.
My problem is that frequently I need insider knowledge from this one employee. I'm supposed to be the public face of this certain area of the company. In reality this happens:
Customer asks a question -> I'm unsure of the answer so I ask the employee -> I tell the customer I have to ask a colleague. I don't hear back from him for maybe two days since he's out of the office -> I respond with the answer.
I'm also required to respond to customer issues the same day, but a lot of times all I can say is "I'm checking on it with X person". Recently, one customer actually just started saying "should X be on this email too?" and to be honest, yes he should be on the email. I'm capable in my field, but there is so much insider knowledge that it's impossible to be effective without asking X questions. Two years in and I still barely understand the systems.
Coming up I have a project that's 10 hours away. X is supposed to give me an overview of what to I need to do, but I know that when I'm onsite something will come up that I don't understand. X will also be unavailable during that time too.
Should I just make it my motto to "do what I can" and let the stress roll off of me?