When casting "repair" on damaged equipment, I often receive no feedback (fizzling or succeeding), just the MP drain. In this chain, I eventually encountered a backfire, after which I could no longer cast on the item, as it said it "needed to be laid flat." Upon relogging, the item had vanished. It was not so close to destruction that I think it was destroyed, and in any case if it was, I was not given the correct message about that happening, only that it had been damaged.

On a different item, after many casts with no feedback, the spell finally succeeded and initiated the animation.

On a third item, I first enchanted it with red magic. After that, it gave proper green magic feedback (lots of fizzles, and finally a success). However, the repair animation did not play.