Maybe SK8 = 8K8, which would mean 8,800 ohm resistance. On second look, it could also be 6K8, which would mean 6,800 ohms. That is the maximum resistance of the potentiometer and can be measured between the two outer pins. The +/- is a tolerance of plus or minus 10% of that value. The pot's total resistance is an unusual value. It may be available, though, as I have not checked. The other value you need is the power capability of the pot, which is usually specified in watts. Based on the relative size in the picture, you might get by with using a similar sized replacement.
Whether the full scale value make a difference is hard to tell without knowing the circuit. However 8,800 + 10% = 9680, so a 10K pot may work. It's a little unnerving to speculate on something used on humans. Be sure to fully validate any repair you make.
John