The first level repairs up to 60% (rounded down). If you had an item with a durability of 8, you could only repair it to 4/8; if the durability was at or above 4, repairing it would have no effect. Is this the problem, or is it not working for things at less than 60%? What happens when it doesn't work, just a drop in mana?
How do I use repair? 
