Over a few years, not surprising there is an imbalance, but I'd check connections on cell #1 in particular and cell #4 to a lesser extent. 3.34V is not that low when charge is removed from the cell. 3.22V however is very low compared to the other 3.... The one was perfectly balanced as it was when I built the batteries, the other had these voltages on the cells:
Cell 1 3.22
Cell 2 3.45
Cell 3 3.45
Cell 4 3.34
There has been a lot of talk of balancers on here so far - but I'd use a bench top PSU to bump up cell #1 to 3.45 and then do same with cell #4.
Then check connections and float with BMS / balancer attached and see how it goes.