If you have the desire to install your own gears I've put together the procedure I used on mine.  I strongly recommend that you DO NOT try this unless you have a good mechanical background  and all the tools and measuring equipment you need.  I didn't have everything I needed at the start but was able to purchase or fabricate what I needed. After I finished and had put 500 miles on the new gears I had a professional check it out and was quite pleased when he told me they were perfect.