to get the end off once the 2 terminals are de-soldered it is just a matter of removing the 2 screws and lifting the end off. as i said earlier, you may have to heat the terminals alternately to get the end off as the wires may still be stuck to the sides.
if you dont have a solder sucker you can try the old way of using wire to suck up the solder. what you do is get a long piece of stranded wire, some wire works better than others, heat up the wire and the solder, and with the iron on the wire and the wire in the solder, the solder should flow to the heat of the iron, then just keep moving the wire through the melted solder. the problem with this is you will need more than what my iron will produce.
here i have the end off and you can see how i had to bend the tab on the right up so i can unscrew it. you will also want to use pliers to unscrew the "washer" on the lug on the left.
this is the solenoid. this contact pushes against the 2 in the next pic connecting the battery to the starter motor. this is what you want to clean and if yours has pitting, you can rotate it to get fresh metal contacting the other 2 lugs.
here is inside the end of the solenoid. your goal here is to remove these 2 studs, clean them rotate them and put them back in.
