Update: I hate giving up on any thing. It's just not in my nature. But at the same time, as I always told my kids and grandchildren, sometimes you have to recognize your limitations and move on.
After my OP last night, I was up until 3AM trying to make that jump and just could not do it. Don't know what's in that chest, and maybe it will show up somewhere else. I've decided to stop trying and move on through the Mines.
I'm how ever keeping the save I have at the lever in case I want to try again before the games over.
