I actually need to get the commenter to turn their comment into an answer but since Bicycles.SE is a practical forum I've actually got some pictures of the results for following their advice and could expand on the answer a little. I'm just not sure if that's the right thing to do?
That's what the "edit" link under every post is there for. :) When you have enough reputation points you can simply edit directly, before that your edits will wait for approval from the community to be visible to other people. Just like it says in the faq and the privileges page.
In general, you should edit the answer if you're improving the answer somehow. (expanding on it, etc) It's also appropriate to comment and suggest improvements (or to use the comments to ask questions).
If you're updating about the progress of your fixes, it might be better to add to your question with the updates, somewhat like I did on this question from almost a year ago: How do I keep my seat from tilting back?