Frank, I'm sad to read of your issues, I to have serious back problems. Actually, I'm disabled due to back issues, and I found I had the same problem as you're experiencing. What I found that helped me, was raising my saw. I always used to sit-up at my saw when using it, that didn't bother me to awful much, but, changing the blade was definitely an issue. I suffered through this for a long time, then one of my buddies suggested that I raise my saw up higher then it was. I raised my saw up about 6", and I lowered my chair by about 2". This made it so that I wasn't looking straight down on the saw as I was cutting, and it made blade changes easier. It made the blade changes easier, because, by having the blade holders at the higher level I didn't have to bend over as far or twist my neck as much to see what I was doing. Maybe trying this suggestion, might help you with your problem. Hopefully it does, as it's not pleasant having back issues. Take care buddy.
Len