I ordered a set of these to put on with my new chain and noticed that they do not have any marks on them to use to align the wheel when you adjust the chain. The picture shows them (although I'm not sure what good they do as shown) but the sliders I got don't have the marks. I called the vendor and they said none o fthe ones they had in the store have the marks. Dos anyone have these and do the A) work, and B) how to you aligh the rear wheel?