My grandfather took my grandmother's treadle machine to the electrical phase.
At one point I asked him: If I wanted to restore the machine back to a treadle, can it be done?
He answered in the affirmative. He said that all the parts that made it a treadle are still there - - i.e. the rotor end of the machine that the belt fits into ... (I don't know the proper names for parts, obviously <g>) ...if you have the treadle, and you have that part ... the rest will depend on how handy your repairman is.