Enough of words, let's see some pix!
One thing I realized when working on this project - I always don't have the right tools when the need arises. Like for this instance, none of my spanners can be used! I've to rely on the adjustable wrench, which is a pain to use for such tight corner. In fact, I've almost all the spanner sizes from 5mm to 26mm, but not a 20mm... And I've 2 of 18mm and 19mm... Thank God I managed to get through with the job.
Now that I've some confident fixing a toilet tank, call or write me if you need help. For a fee of cause... Lol. Tedious job.