may I know what do you mean by 10 peak ? I assume 10mv for peak detect ...

For step charge on cell master, I always use 3mv as peak (I think it means 3mv per cell), for 6cell pack, this is a total of 18mv delta for peak detection.

On the other hand, I am also suffering from the old IB4200 WC cells ... mine are 1 year old and have been well taken care of in the past. Lately, they just tried to "retire" cell by cell. I remove some cells from packs, keep the rest for spare. From original 6 packs of 6cell packs, I now down to 4 packs of 5cell and couple of single cells as spare ...

I charge them at step charge on cell master, 6A for the first 2800mah, rest for 20mah at 0.2A, and continue to charge at 5A, delta 3mV, max 4900mah, always with cooling fans when charging.

Hope this helps.