Originally Posted by
phenry24
https://imgur.com/a/0tPBK
Here is a step-by-step overhaul for ST-6400 shifters. I haven't attempted this, but the steps to access the parts that are likely gummed up look fairly straightforward. But probably best done in one sitting so how everything came apart is still fresh on the mind when everything needs to go back together.
Thanks for the resource. I’ll try that if the flushing doesn’t work in the end