It's normal that you're loosing a bit of selectivity when only running two stages of tuned RF amplification. Now if you were to run your antenna wire to the grid of the third RF amp, it will tune even broader, and with less gain. But that's great news that you've narrowed things down to the first RF stage.
In case you don't already have it, here's more modern schematic that's much easier to navigate.
http://www.atwaterkent.info/TechData...AK09800sch.pdf