Using ether a lot might have damaged your valves/seats or piston rings. I know for a fact that ether will crack your glow plugs, making them inoperative. If you have replaced your glow plugs and still won't go, then do a compression check. I have an IDI that has good glow plugs and good controller that was severely mistreated before I got it. Most of the time it will start, but the compression is a little flaky, and has a hard time starting, but will run fine (or good enough) once it is actually running. I don't use ether on it though, I use gasoline on a piece of cloth to get it started.