I'm not sure of the pass mark but I passed this last week as part of my assessment day , I personally didn't find it that difficult. The instructions are very clear on the test paper, you have to follow an order in which the faults are set out as most important to least important and list the 2 most important faults as your answer. As the test progresses it naturally gets a bit more challenging in where you have to start cross referencing between faults as you will get a combination of a few faults then you need to decide on the 2 most important but you have a fault finding sheet to refer to so as long as you use this you'll be fine , you are provided scrap paper so you can note if needed