Over at MacOSXHints there is a new tip on fixing problems with application services that do not appear properly in the Services section of the foremost application menu. Sometimes the services will not appear, show multiple of the same service, or at other times the menu may show a "Building..." status and never make the services available.
When services stop working in this manner, you can force the system to refresh them by running the following command in the Terminal:
The "pbs" service is provided by Apple to rescan the available services manually in place of having this done by the system or applications. This is provided along with several other options for developers to troubleshoot services provided by their applications, but can be used by the end-user as well.
Keep in mind that just because a service is missing does not mean it is broken. Application services are contextual, so many times you will not see them available if the current working environment cannot send them the information they need. Therefore even if you rescan the services, they may still not show up; however, it will not hurt to rescan them so if you suspect a service is broken then doing this is one step that could help.