What a wonderful story - I'm so glad you rescued it.
I have three treadles (Gramma's Singer, a Household and a Wheeler & Wilson) and I have them all on 'furniture movers' like you do, but mine don't work as well on carpet so I put either plywood, tile or linoleum under them so they 'treadle' much smoother. Each one just needed a new cord and some oil.
Have fun treadling!!!