Hello Sean,
my best advise to you, send them back were you got them from and get a pair of new ones. It is not just a small change over, you have to modify the entire mic and than you still might run into problems with the components made in the former GDR, like connectors, x-formers, etc.
There are only a few mics that were made in the former communist "easter" part of germany that are worthy to get through all this trouble and money to make them studio useable; I would not count the transistor models among them.
If you are located in europe you can send them back to the Gefell factory, they are the only ones that can get them up to specs. but outside of germany/europe it is nothing but trouble.
Some vintage dealers offer them as equal to Neumann Berlin or the in production Neumann Gefell mics, but there are not, as pointed out so many times in postings before.
If you are not a technician or can not do it yourself, you DO will spent more than the new counterparts are, and still have no warranty, etc.
If you do not find a tech in Canada that can do it properly, you might want to check out Robert at QTS here in Eudora/KS
service@baught.com, but aside the problems mentioned above you end up with tons of NAFDA paperwork to avoid customs/fees to send it to the US...
Best regards,