I probably Googled the identical schematic and parts list you have and yeah, it only lists C501, C502, & C503 on that list. BUT, since the list DOES show the values of those 3 caps, can't you just use that to eliminate C501 and C503 from the 3 caps you have on hand and the third one you have removed will define the value of C551 and you can either solder it back in or buy a new one to install in it's place if you prefer?
The schematic I looked at SEEMED to show C551, but it was so hard to make out, it could have been "C531", "C351", or "C331", just as well. Very unclear. Maybe your PCB shows the identity of it more clearly.
C501 is a "10uF 160V" cap and C503 is a "22uF 16V" cap. So remove these from the 3 you desoldered and you should have C551 remaining. Unless you tossed them or mixed them with the other caps from the pcb's you removed.