Thank you for replying andypc42.Unfortunately your alternator must be different to mine.I have just measured my brushes and the dimensions are 7/8"Long-1"Wide-1/4"Thick.There must be some wear on the length of the brushes,as when they are resting on the commutator, the top of the brush is a good 3/16"down from the top of the brush holder.
If anybody has any more information about brush sizes and spring tension i would be glad to hear from you.
Thanks again Andy.