Hello,
The service of Maintenance Optimizer is /sap/bc/webdynpro/sap/wda_mopz_plan
so, it would be like http://host:<8xx0>/sap/bc/webdynpro/sap/wda_mopz_plan?id=<number>
Where <8xx0> is your Webdynpro ABAP port (xx is the system number ) and <number> is the Maintenance Optimizer transaction number .
If you don't fill any number , Maintenance Optimizer will create a new transaction.
Best regards,
Miguel Ariño