Pull off with snipe nose pliers, tweezers or fingernails, press back in the position required. Use appropriate anti-static precautions.
MA = Master
SL = Slave
CS = Cable Select
On an 80 wire (ATA/66 or above) cable (always supports CS), the far end will assume Master, the middle position will assume Slave.
On a 40 wire CS cable (the CS line is cut between the mid and end connector), the middle postion assumes Master, the far end Slave.
On a 40 wire cable without CS support, Master will be assumed on either connector.