I need to replace the middle 42t ring on a Shimano triple (RX100 A550-T) I was given a Origin 8 42t (none ramped and pined) and it just does not want to shift from the 26t low to the 42t middle. Must I get a ramped and pinned 42t for it to shift correctly, and will an FSA 42T be compatible with the inner and outer Shimano rings?

It shifts form the 26t to the 42t middle with the original ring without issue, but it is very worn.