Have you looked at the needle valve in the carb? The starter fluid response sounds like it is a fuel issue rather than anything else. If that needle valve is clogged or if the seat is clogged you will not get any gas to it. Also, see if the float is moving up and down freely. Here is the web site for Matt's carb re-build that may help you.
http://mgonitzke.net16.net/tools/carb_rebuild.pdf
