*thanks Hojo the method works fine*
well first you have to heat the padlock up( on a stove it takes about 7 - 8 mins but a blow torch is best ) until its black or turning white hot..then put it in some cold water - a sink is the best.
what it does when you put it in the water , is that the steam build up pressure and shoots the retaining pins ( or bar ) out of the top of the lock.
here are some pics after i did one this morning :
the retaining bar and cylinder retainer ans spring:

the padlock: top *the furthest pin shaft to your righ is where the cylinder retainer goes

the padlock:

the cylinder and other things:

then you have to re-key it, put back the cylinder retainer and the pin retaining bar and its all done