Cosmos 2264 was launched 930917. Lowered 950331? Decayed abnormally slowly until 950807. The screen snapshot below shows Mean Motion values from elsets. Note that because the orbit correction system apparantly was operating during the entire decay phase, my normal approximation function does not work (the shape of the curve is different, not only the slope)!
Figure 8: Mean motion for Cosmos 2264 as a function of time