Right - assuming that your open and close times are set correctly, you can:
1. Be on the safe side - set the load to 35ms to ensure it will feed even when the halo has just a couple of balls left in the feed neck and thus cant force feed.
2. Be risky, but fast - set the load time to 15ms but beware that when the halo runs empty, it cant force feed the ball stack - resulting in the last few balls being likely to chop. As long as you keep the halo topped up it would be fine though.
3. Long term solution - get the eyes fitted - only costs about £30 + shipping from Racegun Denmark.
Hope that helps,
Tom