If it's working manually but not when your triming it...the orientation must be incorrect. Tucked up kinda high usually. They do get gummed up and won't operate well if you don't maintain them
Get a spark GAP tester. Check spark for 3/8. If you still think it's spark, have you observed the timer plate while it's running? I'd pull the flywheel and examine all the components and linkages.
The gen 1 Evinrude E-tec is the finest outboard ever made....IMHO.
Go to barnacle bills Evinrude web site and learn anything a you need to know about these fine motors.
I'm sure your probably fine...have you tried other test like a spark gap measuring tool?
Has the vro been deleted on that model? If not it needs to be.
It won't do pictures right now (technical issues) but you canale a video and post the link. Not that hard to do.
O ring is to keep water out of the end of the crankshaft.