You can only tell him the symptoms you have you can’t tell him what it is because you don’t know. There is no way to estimate the repair cost. FIRST they need to find out what the problem is. How hard was it to find and get to, what did it need to repair it a hose for 5$ or vacuum tank for 50$. I guess I would try to get an estimate or at least set a limit like you don’t want to spend more than 150$. Take it in and talk to them and see what they say. You can always take it leave with it not repaired. If your lucky if may be a very common problem and they will have an idea what it may be. Sorry that’s the best I can tell you.. Good Luck