There is a way.
I 'boil' the cemented group to separate. Then, with acetone, I work the glued surfaces to remove the glue (completely). This takes a little persistence. Then I thoroughly clean to remove dust then apply a small amount of Canadian balsam. Rejoin the groups, press together gently to spread the balsam and then work the elements to remove any bubbles. Thereafter you let the group sit in a dust free environment with some 'guides' to keep the elements aligned.
It takes about 3-4 weeks at room temperature to cement. Remove any excess Canadian balsam then re-blacken the element sides then re-assemble. Should be as new.
Others may suggest different glues. I suggest the balsam as it is easy to rectify any mistakes made.
Enjoy and have fun