Sarah, you should be able to easily replace the skates (either old or new types) without having to dismantle the loco chassis. The older type just requires the removal of a screw which is fully accessible without removing anything else, and the newer ones (identifiable by NOT having a screw that holds them in place) can just be "wiggled" out of their fittings. In both cases, the only thing you need to be careful about is not to let the small spring that tensions the skate against the track fly out and get lost - it's a good idea to put something like a wide cardboard box or a washing-up bowl on the table and hold the loco inside said receptacle while you remove the skates, then the springs will hopefully not "sproing" out across the room and disappear forever in an inaccessible corner......
However as you're on a budget and may not want to buy new replacement ones, then yes - you can indeed bend an "overshoe" out of a piece of thin brass strip, and crimp it firmaly in place with some pliers; indeed some people do this deliberately, with the brass strip being narrower than the original skate, to avoid problems with the skates shorting on some metal point frogs when using certain track types (such as Peco code 250) - the narrow brass strip still makes contact where it needs to, but reduces the contact width to avoid the shorting problem caused by the original skate width.
Jon.
