The best approach is to put the truck in for the test. If there are defects and it fails, the tester will provide you with a list of the defects. You can then work on getting those items sorted out. If the defects relate to items which require a test lane and use of the equipment such as the brake tester etc, you will have to pay a retest fee but if they are visual items, there is no retest fee. It will then pass "defects rectified".
This is better than trying to decide yourself what the defects are. You could spend a lot of time and money trying to make sure that everything is perfect and the truck could still fail the test. Apart from that you might have spent time on items that wouldn't actually have failed at all, because you don't have the experience of the tester and some items are to some extent subjective.
The other chaps suggestion about getting hold of a testers manual is a good idea also - from the point of view of increasing your knowledge about trucks and keeping them safe and roadworthy.
JD
January 2009