Greg:
I've forgotten the details but the most common electric tongue jacks I've seen, like the ones used on Airstream and Avion travel trailers, were manufactured by a company or companies known as H & H or Barker. I researched this several years ago when deciding whether to rebuild or replace one. H & H or Barker (I think one company bought the other or changed names) has a website, a technical section that will answer your questions, and parts available.
If you can't find anything on the web, talk to an Airstream owner or dealer who sells them. The H & H or Barker tongue jacks installed on Airstreams provide a warranty and parts booklet that is provided in owner's packets. You might be able to borrow one.
Harvey