I am getting ready to replace the lower shift shaft seal on a pre-alpha 140 drive. I think I remember reading somewhere that you don't want to actually remove the shift shaft as the dog at the bottom can get out of alignment and you then have to take the entire lower unit apart. Is this true? Is it better to loosen the bushing and slide it up and not move the shaft? Is that possible? The manual is very vague on that point and instructs you to remove the shaft with no warnings of the ramifications of doing so. Can someone please clarify that? Thanks.