Perhaps an older version of PGML.pl would work for you. Try this one and see if that does it. (Use the "raw" button to get an un-annotated version, and save it to PGML.pl on disk, then download to your server.) Note, however, that features have been added to PGML over time, and so if the problems you are trying to use contain any of the, they might not work properly.
WeBWorK Error
WeBWorK has encountered a software error while attempting to process this problem. It is likely that there is an error in the problem itself. If you are a student, report this error message to your professor to have it corrected. If you are a professor, please consult the error output below for more information.
Error messages
Error detected while loading [PG]/macros/contextTypeset.pl: PG_macro_file_eval detected error at line 246 of file [PG]/lib/PGloadfiles.pm Can't call method "copy" on an undefined value at line 753 of (eval 34527), chunk 1. The calling package is PGloadfiles Died within PGloadfiles::compile_file called at line 334 of [PG]/lib/PGloadfiles.pm from within PGloadfiles::loadMacros called at line 418 of [PG]/macros/PG.pl from within main::loadMacros called at line 1468 of (eval 34521) from within main::_PGML_init called at line 360 of [PG]/lib/PGloadfiles.pm from within PGloadfiles::loadMacros called at line 418 of [PG]/macros/PG.pl from within main::loadMacros called at line 17 of (eval 34369)
Error details
Problem11 ERROR caught by Translator while processing problem file:local/setcombinatorics/BallyGoBackDeans_OPL.pg **************** Error detected while loading [PG]/macros/contextTypeset.pl: PG_macro_file_eval detected error at line 246 of file [PG]/lib/PGloadfiles.pm Can't call method "copy" on an undefined value at line 753 of (eval 34527), chunk 1. The calling package is PGloadfiles Died within PGloadfiles::compile_file called at line 334 of [PG]/lib/PGloadfiles.pm from within PGloadfiles::loadMacros called at line 418 of [PG]/macros/PG.pl from within main::loadMacros called at line 1468 of (eval 34521) from within main::_PGML_init called at line 360 of [PG]/lib/PGloadfiles.pm from within PGloadfiles::loadMacros called at line 418 of [PG]/macros/PG.pl from within main::loadMacros called at line 17 of (eval 34369)