3.38 VPC is quite low. You'd really want to go to around 3.55 VPC, which was 142 V for your 40-cell configuration.Incidentally, what gave rise to the problem is that I added two cells to a 40 cell pack. Even with 42 cells, the old programming should cover the charging… It’s a 520V algorithm 133-142V in 1V steps. I have drained the battery down below 134V, and I’m trying to charge it to 142, Which is about 3.38V per cell.
If you're stuck at setting 7 (139 V), then even a battery drained to 134 V (it might have sprung back a bit in voltage) might look too high to start charging. And 139 V / 42 cells = 3.31 VPC, not even at the resting voltage of a 50% charged cell.
I think you will need reprogramming for about 42 x 3.55 = 149 V. Elcon in California could do it (if they are still interested in these older models), and Paul could probably do it. Though he may have a slightly different lithium algorithm than the "520V" (nothing to do with voltage) "curve" or "algorithm". Or you could do it yourself; the instructions and software are on this forum, but it's a bit daunting for most.
It's also possible that your charger's voltage measurements have drifted over the years, so it could do with a calibration. I believe that Paul can do this too, but it wipes out your existing charge program. No problem if it is going to be overwritten anyway for higher voltage.
I believe that your 120 V hardware can go up to 154 V (at full power; 161 V at half power).