Welcome. As WIChix said the serial number indicates it is a 27 and indeed many are missing the front slide plate. Fortunately, replacement plates are available. They don't have the same finish but they do make the machine operational.
https://shop.sew-classic.com/Slide-C...7-27-55504.htm
A presser foot is available at
https://shop.sew-classic.com/Low-Sha...5321-45321.htm
As for the 111W155 not having a reverse, if you really need it -- there are several work-a-rounds.
Janey - Neat people never make the exciting discoveries I do.