What do you mean you GLUED the oring to the nozzle?!?!
In all honesty you probably should have done a little more research. If you were able to afford a new spring you can afford an $8 nozzle with double o-ring.
Test for compression first before you even consider getting a new spring. The problem generally lies with with the piston head and the cylinder if increasing spring strength yields little to no significant difference. Most guns barely need an m10 for 350 fps so you KNOW that there might be something wrong.
The misfeeding is probably because the nozzle isn't able to push forward all the way with a hard crusty nitrile o-ring stuck to it and the cylinder head and isn't pushing the bb's out. I would recommend scraping that thing off if you have a chance to salvage it.