Look at this:
That is mapnik, and it looks fine. Switch to osmarender, and see how many roads in the eastern and southern part gets shortened. There are also some blank tiles with sea color on land.
I know that I can go to www.informationfreeway.org and request re-rendering, but only at zoom12. I have done that sometimes and it works fine. (e.g. when changing a road from primary to trunk with no other changes.) But this only works for the detailed zoom levels, not for the zoomed-out map at 9.
I have also tried adding some points to those roads, that did not help either. How can this be fixed?