You need to buy a new #2 idler gear and the spring clip that goes on it. The gear has been redesigned to engage the flywheel gear better. You may still have problems, even after replacing these two parts. That said, there is only one REAL fix for your starter, but you have to pull the side cover and check to see if your bike has a hole machined for a fork shaft (see the picture in the first link). Check the links I have supplied for information.
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