Why is it leaking? Caused by ...?
Not just curious, depending on reason then it may more or less important to dig deep.
If it is "Just a leak" and your only ambition is to tighten, then it may be possible to to without removing the shaft. If you want more, and really be sure to make a good job, then I recommend to remove everything that just might be in your way.
Done similar job, had to remove shaft otherwize I wouldn't have sufficient access. Job in itself is rather strightforward. Important to see to that no water stays "inside".
/J
Not just curious, depending on reason then it may more or less important to dig deep.
If it is "Just a leak" and your only ambition is to tighten, then it may be possible to to without removing the shaft. If you want more, and really be sure to make a good job, then I recommend to remove everything that just might be in your way.
Done similar job, had to remove shaft otherwize I wouldn't have sufficient access. Job in itself is rather strightforward. Important to see to that no water stays "inside".
/J