SE24 - Unable to restore Private Section of Z Class using Version Management

Greetings experts,

I've encountered an issue in TX. SE24 while attempting to restore the private section of a class to a previous version.

Some context first: The attributes of this class contain very long STRING constants used for e-billing. Upon adding a new attribute, I'm unable to activate the class, and SAPGUI is displaying the following error:

"Literals that take up more than one line are not permitted."

Upon inspecting the code for the private section, I saw that one of the already-existing constants in the Z class is extremely long and does not have a closing " ' " at the end, which causes certain parts of the code to appear in red and thus is unable to activate.

I tried bringing back an older version of the include through Version Management, but so far this has been unsuccessful. Upon retrieving the old include, the one that appears is still the incorrect one.

I have also attempted to remove the faulty attribute through SE24 to make it from scratch, but the error I get is:

Error OO401 "You cannot perform this action in modification/enhancement mode"

Note 2629624 indicates that the change has to be performed on the original system, but it is no longer available since this is a very old class.

Is there any way I can change the Private Section manually? The old, working version of the Private Section seems to be using '&' symbols to concatenate the different parts of the long STRING constants, so finding a way to copy this code may be the solution.

Kind Regards,

Ángel.