Master 570 question

[sambob]

I noticed a solid lug under the keyway and an exposed pin In the side can you take this thing apart and change the pins around??

[I Pik U]

I'm not familiar with the 570, but it looks similar to the Americans.
Look into the shackle hole, when opened. If thre's a screw (I assume not with your description), you can undo it to remove the cylinder cover and cylinder.
If it's the soild lug your refering to, you can drive it out with a punch and reuse it. Use a punch slightly smaller in diametre than the lug, and put the punch down the shackle hole onto the end of the lug. Place the bottom of the body of the padlock on a slightly open vise (or similar) so that the body rests on the vise, but the lug can be driven out the bottom by your punch. Once the lug is out, you can remove the cylinder cover and cylinder for rekeying. You can reassemble it all, tapping the lug back in, then using a larger punch down the shakle hole to re-pean the lug.