Sounds like you found your problem. Cells are roughly $500 give or take...a few hundred, all depending on battery type and size. Wouldn't put much money in a battery older than 4 years, depending on your application.

Both 12 and 18 were at less than 1.75 volts gravity level of 12 was 1100. 18 was 1000

I did load test in process found cell 12 and 18 bad. Battery is less than 2 years old.

I would perform a load test on the battery. Do you know the age of the battery? Battery s/n?

It sounds like you have a battery problem.

I let it run down to 40% charged it. Till charger shut off it then read 100% soon as I used carriage and turned key off and back on it dropped to 70%. Could there possibly be something wrong with the regen from hydraulic motor. I believe that when the mast is lowered it recharges battery some how? Or am I incorrect in my understanding of this?

I am not sure if this applies to your truck but some of the new systems require the battery to be below a certain percentage before a recharge will reset the display. Try running the truck until the display reads below 50%. Then recharge and check it.

I put on charger again let it charge till it said it was charged. Tested voltage at battery 40.10 v./ 39.5v at access 8 panel. On lift it shows battery to be at 61%.

I did it was 37.85 volts. Though something happened when I used the carriage the voltage dropped from 84% to 61%. Going to top and back down 1 time.

I WOULD CHECK BATTERY VOLTAGE FIRST BEFORE ANYTHING ELSE