If you can put the e unit in a vise to gently hold it and connect your jumper wires to the two side contacts were the wire is soldered and you should see it operate the roller contact. You can replacements for the sliding shoes by getting 2 #2036-122 rollers with bracket. $1.75 each at the train tender. Just release the copper clip inside the insulator and pull old part out and slide new one in...
Marty